Glitched Item Duplication Guide

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Glitched Item Duplication Guide

The following is a guide / documentation for glitches that can be used to duplicate items in Minecraft. While this post is intended to serve as a guide for Minecraft speedruns done in glitched categories, note that this page can also serve as a general resource for duping items in Minecraft.

While there are many widely known methods for duplicating specific items or entities, this guide will focus on:

  • “General” duping methods, i.e. ones that will duplicate any item (not limited to specific items)
  • Methods that can be done with no/very little resources.

Please note that this guide is currently highly incomplete and some information contained within may not be confirmed or fully tested on different computer hardware and software. In general, (external) duplication glitches are highly dependent on both the computer hardware and (surprisingly) the computer OS, and due to the low number of glitched players and testers, several duplication methods may not work / work differently than known on untested hardware. In particular, duplication methods have not been widely tested on Linux operating systems, so I would like to encourage members of the community to test and document duping behavior on those systems.

In general, duping methods (and Minecraft glitches in general) can be divided into three categories:

  • “Internal” - methods that do not involve leaving or quitting the world in any way.
  • “External Persistent”, or “Persistent” - methods that involve relogging / quitting the world, but do not involve closing or crashing the game instance.
  • “External Interrupting”, or “External” - all other methods which involve crashing or quitting the game instance.

Here this document will go over these categories separately.

Internal Duplication Methods

In general, there are few methods inside the actual game itself to duplicate items. Internal duplication glitches usually involve a way to corrupt item stacks, to obtain a version of an item that is self-replicating and not normally obtainable.

Zero Stack Duping, 1.0-1.8.9

Zero stack refers to a stack of items with the number of items being zero. This is not normally obtainable except under certain circumstances. When the player attempts to drop an item from this stack, the item stack will become a “negative stack”, but items will be dropped according to normal item logic.

The player will not be able to see the itemcount until it was added in version 1.6. Before, it will simply appear as if the item is a single item (stack size 1).

Version Range: 1.8-1.8.9. However, different ways of obtaining the zero-stack may only work in certain versions.
Hardware: Should work the same on all hardware, but lower game FPS is slightly easier to time.
Behavior: Linear with item multiplication rate n.
Multiplayer?: Yes, but difficult due to the low TPS of some multiplayer setups.

Instructions:

  1. Obtain a zero stack.
    • This can be done through several methods but usually all of them involve taking an item out of a container on the same tick that container is destroyed.
    • Several methods are known:
      • Taking an item out of a minecart with chest as it is being destroyed by a cactus or fire (1.0-1.8.9)
      • Hotkeying an item out of a container as it is being destroyed by an explosion (1.0-1.8.9)
      • Container Wireless Mining. (1.3.1-1.5.2)
      • Putting items into a crafting table and entering a nether portal with the GUI still open (1.0-1.1)
  2. Drop items from the zero stack. This should create regular (non-glitched) items. This can be done by dropping items outside of the inventory using right click, dropping items directly into the inventory, or any container (only works before 1.6), or dropping the items using a dispenser or dropper.

Video Examples:

Crafting Book Item Transmutation (Crafting Table), 1.12

The crafting table was introduced in version Minecraft 1.12.0 - however, numerous bugs existed with displaying the example items and it was very easy to desynchronise item locations in the crafting GUI. This “duping” method actually transforms some amount of one item into another item. However, if the player has easily multiplied items (wood → sticks, ingots → nuggets) then this item transmutation can self-propagate and become an item duplication technique.

Version Range: 1.12(.0) ONLY. patched in 1.12.1.
Hardware: Doesn’t matter. Lower game FPS is slightly better but it really doesn’t matter all that much.
Behavior: behaves as an item transmutation glitch that can be used to infinitely propagate newly created items.
Multiplayer: Yes! (works exactly the same in co-op, and not dependent on the server TPS)

Instructions:

  1. Have a valuable item to be duped “A”, and a large amount of some “junk item” “B”. The amount of B cannot be more than 32.
  2. Have B in the off-hand and A in the main-hand
  3. Simultaneously press your off-hand hotkey (to swap hands) and open and crafting table.
    • This is a frame perfect input. Play around with the timing.
      1. If you have succeeded, B should appear to be both in the offhand and the main hand. A will appear to have disappeared.
  4. Put B into the crafting grid and open the crafting book
  5. Click any recipe in the crafting book
  6. Exit the inventory. The stack of B should have been transformed into a stack of A, with the amount being the sum of the original amounts of A and B.

Video Examples:

Crafting Book Item Transmutation (2x2), 1.12

This method works similarly to the first method, but uses the player’s crafting grid instead. This method is significantly more difficult and should only be used if the player does not have easy access to a crafting table.

Version Range: 1.12(.0) ONLY. patched in 1.12.1.
Hardware: Doesn’t matter. Lower game FPS is slightly better but it really doesn’t matter all that much.
Behavior: behaves as an item transmutation glitch that can be used to infinitely propagate newly created items.
Multiplayer: Yes! (works exactly the same in co-op, and not dependent on the server TPS)

Instructions:

  1. Have a valuable item to be duped “A”, and a large amount of some “junk item” “B”.
    • Unlike the previous method, the stack of B can be more than 32.
  2. Open your inventory and open the crafting book.
  3. Put the stack of A into the 2x2 crafting grid.
  4. Simultaneously, hotkey the stack of A out of the grid and close your inventory.
    • The timing of this is frame perfect and you may have to play around with your timing to get it to work.
  5. Re-open your inventory.
    • If you have succeeded in step 4, the crafting grid will look empty but whatever A crafts into will appear in the crafting output.
    • In the event A is an item that doesn’t craft into anything, it’s impossible to tell.
  6. Hotkey B into the slot where A was originally.
  7. Click any recipe in the crafting book.
  8. Exit the inventory. The stack of B should have been transformed into a stack of A, with the amount being the sum of the original amounts of A and B.
    • An additional ghost stack of A (with amount corresponding to the original amount of A) will be created. You can get rid of them by clicking on the stacks of A you now have.

Video Examples:

There exist many other well-known methods of “true” internal duping, usually involving tampering with the game’s internal chunk saving or creating corrupted items. These are not well documented and usually require significant resources so for now I won’t include them here.

External (Persistent) Duplication Methods

These methods all involve relogging, but not crashing the game instance. Currently, all methods that fall into this category are only known to work in versions 1.7.2-1.11.2.

“Drop Dupe”, 1.8-1.8.9

It’s unknown who originally discovered this method. However, the first runner to use it in speedruns was the runner oldGanon.

Version Range: 1.8-1.8.9
Hardware: worse hardware is better.
Behavior: Exponential with item multiplication with rate 2^n. However, it is easily chainable, so that only one “setup” needs to be performed, making the item multiplication linear with rate 2n.

Instructions:

  1. Have the items in your inventory.
  2. Drop all of the items you have at the same time.
    • This can be done by putting the items to be duped into the player crafting menu and exiting the inventory. This will drop all the items at the same time.
    • The maximum number of item stacks that can be duped at one time is therefore 5, since 4 can be contained within the crafting menu and one can be held with the mouse.
    • More can be duped with a crafting table, up to 10 stacks.
  3. Pause the game on the exact tick the items are picked up
    • This can be done by normal pause buffering, but can also be done by using the “Statistics Advancing” technique on 20fps.
  4. If you are already not on high-(ish) RD, then the RD should be raised.
    • How much depends on the hardware and initial RD, but can be anywhere between nothing (zero) or up to 24 rd. You should test on your own hardware.
  5. Relog. The item will have been duped once.
  6. If you pause immediately when the world opens (pause on lost focus), you can continually relog to duplicate the items over and over again, instead of re-dropping the items. However, depending on your hardware, it may fail at some point.
    • Generally, the dupe is more inconsistent while in spawn chunks, or in the end.
    • Food items and crops (bread, carrots, etc.) should not be duped next to villagers. The villager will continually pick up the items instead of it landing in your inventory.

Video Examples:

“Exponential Persistent Dupe”, 1.7.2-1.11.2

This method was discovered by SpeedNintendo and Crafterdark in 1.8, and later discovered to work in 1.7 and 1.9-1.11 by me (zelario). However, due to the lack of 32rd in vanilla 1.7, and general optimizations to chunk loading in 1.9, it is much less consistent in 1.7 and 1.9-1.11 than in 1.8.

Version Range: 1.7.2-1.11.2
Hardware: worse hardware is better, especially in 1.7/1.9-1.11. 1.8 is a laggy version so to save RTA better hardware might be better in 1.8.
Behavior: Exponential with item multiplication with rate 2^n.

Instructions:

  1. Have the items in your inventory.
  2. Drop the items on the ground.
    • Not yet tested/confirmed to work when the item is placed in containers.
  3. Pause and increase the RD to create lag.
    • 32rd is theoretically the best in 1.8, but might create significant lag. A lower RD might be optimal.
    • 16rd is the max in 1.7, and seems to be barely enough to work.
    • The timing of the pauses and inputs is inconsistent and you might need to play around with it (especially in 1.7). Doing the dupe in 1.7 might not be possible on all hardware, and all of the settings changes and pauses must be done quickly.
    • Setting the game fps to 10 fps might be required for macOS users.
  4. Unpause and then pause quickly after, and re-lower the RD back to a low value.
    • Re-lowering the RD is not required (and actually worse) in 1.9-1.11
  5. Pick up the item and quit the world.
    • In 1.9-1.11, it’s relatively inconsistent, but spamming F3+A before the item gets picked up seems to help.
  6. Quickly, re-enter the world. The item should be duplicated.

Video Examples:

External (Interrupting) Duplication Methods

These methods all involve quitting or crashing the game instance. In general, these methods all involve performing a partial world corruption on the Minecraft world containing the items, causing the game to place the items in two locations at the same time when the world is saved.

In general, there are three different ways of crashing the game. Specific terms will be defined here to avoid confusion:

  • “Force Quit” - “hotkey crashing” the game (Alt+F4, cmd+Q, etc.)
  • “Crash” - using Task Manager to end the Java Platform Binary on Windows, or using Activity Monitor to end java on macOS (and the Linux equivalents)
  • “Kill” - killing the instance, either by using the relevant buttons in MultiMC/Prism/etc, or ending the “javaw” task in Task Manager on Windows, or typing a java-killing command on macOS/Linux terminals.

“Alt+F4 Dupe”, 1.0-1.12.2 (Windows, macOS)

This is the classic method of duping which works from 1.0-1.12.2.

Version Range: 1.0-1.12.2 (Windows), 1.0-1.5.2, 1.8-1.12.2 (macOS). 1.5.2+ on macOS seems to be inconsistent. Theoretically works on 1.13, but the performance in most cases is too bad.
Hardware: medium-low level hardware is best
Behavior: Exponential with item multiplication with rate 2^n. On worse hardwares, it can be “chainable” with rate 3^n, but this seems to be the limit.
OS: Windows, macOS. Not currently known if it works on Linux systems or not.

Instructions:

  1. Have the items in your inventory
  2. Remove the items to outside of the inventory (either by dropping them or putting them into a container)
  3. Save the game (either by pausing or relogging)
  4. Lag the game by increasing the RD to an unspecified amount depending on your hardware
    • Ismexion has reported that spamming F3+S also works
  5. Pick up the items.
  6. Force quit the game.
    • Any method of crashing the game should theoretically work
    • Simply closing the game (by clicking the “x” on the window) also works in versions before 1.6.x
  7. Rejoin the world. The items should be duplicated.

Video Examples:

“Modified Alt+F4 Dupe”, 1.0-1.13.2 (Universal?)

This is the modification of the 1.0-1.12.2 Alt+F4 Dupe for Windows. This version works on macOS, as well as Windows systems with very bad hardware. This dupe was independently discovered by several runners on different versions (discovered on 1.13.2 (Windows) by Ismexion, 1.12.2 (Windows) by Sirpalmtree, and 1.6.4 (macOS) by me (zelario)). While this is an alternate duplication glitch for the 1.0-1.12.2 versions, it’s the only working dupe known for 1.13.x versions.

Version Range: 1.0-1.13.2. (pre1.5 versions not yet tested)
Hardware: worse hardware is better
Behavior: Exponential with item multiplication with rate 2^n.
OS: Windows, macOS. Not yet tested for Linux. (Linux testing is needed, as there’s a good chance this might work)

Instructions:

  1. Have the items in your inventory, and create lag by being on 16 RD (1.7.2-) or 32RD (1.8+).
  2. Remove the items from your inventory (either by dropping it or placing it in a container).
  3. Save the game by pausing, and or relogging (relogging seems to be less consistent)
  4. Pick up the items.
  5. Pause the game and IMMEDIATELY AFTER close the game using one of the following methods:
    • Kill the game. (works for 1.0-1.11.2)
      • Timing is somewhat lenient (must be faster than ~1-2s)
    • Force quit the game. (works for 1.0-1.13.2)
      • Timing is relatively tight and the game must be closed immediately after the game is paused.
      • Timing for 1.13.x version specifically is relatively lenient (must be faster than ~1s)
  6. Rejoin the world. The items should be duplicated.

Video Examples:

“Single-Process Method”, 1.14-1.21.11 (Windows, macOS)

The single-process method is named as such (in contrast to the multi-process method) as the game only needs to be crashed once to perform the dupe. However, in general it is less consistent than the multi-process method.
It’s unknown who discovered this duplication glitch. However, it is occasionally called the “sheeperino dupe” after the first runner to use it in speedruns.
The discovery that a delay and lowered fps must be inserted into the process to make the dupe function on macOS was discovered by the YouTube user “Rodrigo D.” in 2020. However, the video showcasing this has since been deleted.

Version Range: 1.14-1.21.11. It has been reported to work on 26.1+ by several YouTube videos but it’s not been confirmed by anyone in the MCSR community at this time.
Hardware: not yet tested on a wide range of hardwares, medium-strength hardware is the best(?)
Behavior: Exponential with item multiplication with rate 2n where n is the number of dupes. Theoretically “chainable” to achieve 3n or higher but not tested yet.
OS: Windows, macOS (with modifications). Not currently known to work on Linux (tested with 2 users).

Instructions:

  1. Have the items in your inventory and save (either relog or pause)
  2. Windows users (nsla) have reported that the dupe will not work on the first attempt unless the player relogs at least once before.
  3. Lag the game by increasing the render distance to 32.
    • Both render distance and simulation distance should be raised in 1.18+
    • MacOS ONLY: You must also set your FPS to 10.
    • MacOS ONLY: The player must unpause to let the world load. The player must wait an unspecified amount of time while paused or unpaused (but paused saves IGT), usually 15 seconds or more, at this time for the duplication to work. It doesn’t work if this step is not followed, for unknown reasons.
  4. Remove the items to a space outside of the inventory. This can be the following:
    • Dropped on the ground. This only works for versions 1.14-1.16.5.
    • Placed in a container, like a chest. This works for versions 1.14-1.21.11 (26.1+ unconfirmed)
    • Placed in a crafting slot (either the players or that of a crafting table). Tested to work for 1.14-1.16.5 but not further (but it is expected to work).
  5. Crash the game.
  6. Rejoin the world. The items should be duplicated.

Video Examples:

“Multi-Process Method”, 1.14-1.21.11 (Universal)

The multi-process method is named as such (in contrast to the single-process method) as the game only needs to be crashed twice to perform the dupe. However, in general it is more consistent than the multi-process method.
It’s unknown who discovered this duplication glitch, but it was discovered before the single-process method.

Version Range: 1.14-1.21.11
Hardware: Worse hardware is better. Should be fairly consistent on most hardware though.
Behavior: Exponential with item multiplication with rate 2^n where n is the number of dupes. Theoretically “chainable” to achieve 3^n or higher but not tested yet.
OS: Windows, macOS. Should work on Linux but not yet tested.

Instructions:

  1. Have the items in your inventory and save (either relog or pause)
  2. Lag the game by increasing the render distance to 32.
    • Both render distance and simulation distance should be increased in 1.18+
  3. Remove the items to a space outside of the inventory. This can be the following:
    • Dropped on the ground. This only works for versions 1.14-1.16.5.
    • Placed in a container, like a chest. This works for versions 1.14-1.21.11 (26.1+ unconfirmed)
    • Placed in a crafting slot (either the players or that of a crafting table). Tested to work for 1.14-1.16.5 but not further (but it is expected to work).
  4. Force quit the game.
    • This should cause the game to attempt to do an “emergency save” - the game should go to a gray or black screen, or freeze, but the window should still be open for a short amount of time.
  5. During the above described game “emergency save”, the game should be crashed.
  6. Rejoin the world. The items should be duplicated.

Video Examples:

“Multi-Process Method”, 26.1+ (Universal)

Due to changes in the world file structure made in update 26.1, the old multi-process method no longer worked. It also appears that the single process method no longer works, or was made less consistent. Discovered by me (zelario) in 2026, and was confirmed by Scribble on Windows. Linux testing is needed.

Version: 26.1+
Hardware: Not yet tested with a wide range of hardware (worse hardware is better?)
Behavior: Exponential with item multiplication with rate 2^n where n is the number of dupes. Theoretically “chainable” to achieve 3^n or higher but not tested yet.
OS: Windows, macOS. Should work on Linux but not yet tested.

Instructions:

  1. Have the items in your inventory.
  2. Remove the items from your inventory, either by putting it in a container or dropping it on the ground.
  3. Save the game by either relogging or pausing
  4. Lag the game by increasing the render distance and simulation distance to 32.
  5. Pick up the items.
  6. Force quit the game.
    • This should cause the game to attempt to do an “emergency save” - the game should act as if the world was closed and should display “saving world…”
  7. During the above described game “emergency save”, the game should be killed.
    • Simply crashing the game works according to Scribble but I wouldn’t be sure that this would work on all OS
  8. Rejoin the world. The items should be duplicated.

Video Examples:

Time Travel Duping, 1.7.2+

There are a number of methods to dupe using the “time travel” technique that are known. While a detailed discussion of time travel is outside the scope of this guide, the general idea is that the game will save chunks when they are no longer loaded, and that if the player then kills the instance (which will crash the game without saving) the player can manipulate the items to be in two places at once. This behavior has been confirmed for versions 1.7.2+ on at least some hardware but exactly what versions it works on are extremely inconsistent between hardware and in general few people have gotten it to work on versions before 1.14 on WIndows, and versions before 1.18 on other OSs with a few exceptions. In general, this technique is not consistent and it should not be a primary method of duplicating items.

Instructions:

  1. Have the items in your inventory, and save (either by relogging or pausing).
  2. Put the items in a container.
  3. Unload the container. This can be done in several ways:
    • Change dimensions (i.e. enter a nether portal).
    • Run away so that the container is outside of your RD. (low RD is good for this)
      • This doesn’t work in perma-loaded areas, like spawn chunks or the end island.
  4. Kill the game instance.
  5. Rejoin the world. Your world should have reverted back to when you originally saved, with the exception of the items in the container (and any other changes to the world that were unloaded).

Video Examples:

Some of the “holes” in the known dupes for certain version/OS combinations could be filled with more testing of these techniques, especially on Linux operating systems (where results are not well known). I would appreciate any feedback on this ^_^

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