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  1. Minecraft: Java Edition
  2. MC-115404

Items can duplicate if the item entity gets modified

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    • Confirmed

      The bug

      A player in Survival or Adventure mode picking up and dropping items modified by the /entitydata command can duplicate the items.

      How to reproduce

      I made a quick little video, but I had to shove it on dropbox because of the 10MB limit
      Link: https://www.dropbox.com/s/bqyjpazljppkirr/2017-04-04%2021-56-30.mp4?dl=0

      1. Place a repeating command block, enter for example the following command (you can modify actual item entity tags as well) and activate it 
        /entitydata @e[type=item] {SomeCustomOrExistingTag:1b}
      2. Place different variants of an item (for example different colored wool) in your hotbar
      3. Switch to Survival or Adventure mode 
        /gamemode survival
      4. Drop all items in your hotbar by either pressing Q or Ctrl + Q
      5. Select the first hotbar slot and keep pressing Q or Ctrl + Q
        → After some time you should see that the dropped items have been duplicated

        1. entitydatacommand_itemduplication.mp4
          5.88 MB

          [MC-115404] Items can duplicate if the item entity gets modified

          [Mojang] Nathan Adams added a comment -

          Okay scratch my previous comment. MC-114879 is indeed actually fixed, but this is an edge case when the item entity was modified afterwards (such as /entitydata or a more simple case of "throw another item into the pile", as MC-117217).

          [Mojang] Nathan Adams added a comment - Okay scratch my previous comment. MC-114879 is indeed actually fixed, but this is an edge case when the item entity was modified afterwards (such as /entitydata or a more simple case of "throw another item into the pile", as MC-117217 ).

          [Mojang] Nathan Adams added a comment -

          After testing this out, I can reproduce it but don't need /entitydata (or any other commands) running. It seems that this is just MC-114879 and that we didn't fully fix MC-114879. I will reopen that and close this issue.

          [Mojang] Nathan Adams added a comment - After testing this out, I can reproduce it but don't need /entitydata (or any other commands) running. It seems that this is just MC-114879 and that we didn't fully fix MC-114879 . I will reopen that and close this issue.

          Nope. added a comment -

          @tryashtar I am able to reproduce the issue in both pre-releases, I used a fresh superflat world with default settings and I found that dropping a full hotbar resulted in multiple of those items being duplicated. Expanding on what Marcono said, I probably get successful results due to the fact I mostly test with multiple types of stone.

          Nope. added a comment - @tryashtar I am able to reproduce the issue in both pre-releases, I used a fresh superflat world with default settings and I found that dropping a full hotbar resulted in multiple of those items being duplicated. Expanding on what Marcono said, I probably get successful results due to the fact I mostly test with multiple types of stone.

          Marcono1234 added a comment -

          It looks like you need to have different variants of the same item. I was able to reproduce this with only 2 same items as well but it happened less often there.

          It appears the items duplicate when the player has just picked up the items (not even client-side yet?) and already drops them again.

          Marcono1234 added a comment - It looks like you need to have different variants of the same item. I was able to reproduce this with only 2 same items as well but it happened less often there. It appears the items duplicate when the player has just picked up the items (not even client-side yet?) and already drops them again.

          [Mod] tryashtar added a comment -

          I really can't reproduce this, after following your instructions for several hundred items. Can you really still get this to happen in 1.12 pre-2?

          [Mod] tryashtar added a comment - I really can't reproduce this, after following your instructions for several hundred items. Can you really still get this to happen in 1.12 pre-2?

          Nope. added a comment -

          Just updated the affected versions.

          Nope. added a comment - Just updated the affected versions.

          Daggard M added a comment -

          In the latest snapshot as well (17w18a)

          Daggard M added a comment - In the latest snapshot as well (17w18a)

          user33 added a comment -

          Still in 17w17b

          user33 added a comment - Still in 17w17b

          [Mojang] Nathan Adams added a comment -

          Please let me know if this is still an issue, otherwise it was fixed some versions ago.

          [Mojang] Nathan Adams added a comment - Please let me know if this is still an issue, otherwise it was fixed some versions ago.

          Marcono1234 added a comment -

          Can confirm this for 17w14a, it looks like you have to be in Survival or Adventure mode

          Marcono1234 added a comment - Can confirm this for 17w14a, it looks like you have to be in Survival or Adventure mode

            dinnerbone [Mojang] Nathan Adams
            TheRedstoneRazor Nope.
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              Created:
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