Minecraft Version

1.20.1

What happened?

Bug Report: Item Duplication Exploit via "Additional Items" Menu
Description:
There’s a serious item duplication bug in the mod that allows players to duplicate any item, including rare and modded gear.

Steps to Reproduce:

Die with items in your inventory.

Press U to open the "Additional Items" menu.

Click on the curved arrow icon in the top-right corner — this returns the items to your inventory even if you're far from your body.

Now walk back to your death point and loot your body as normal.

You’ll receive duplicates of all items that were returned via the U menu and picked up again from your corpse.

Impact:

If combined with a backpack mod, you can duplicate the entire contents of the backpack (e.g., diamonds, modded tools, enchanted gear).

This completely breaks gameplay balance — especially in SMP or progression-based packs.

Proof:
I'm preparing a video demonstration of this exploit for YouTube if verification is needed.

Relevant Log Outputs

No response

Press U to open the "Additional Items" menu.

Click on the curved arrow icon in the top-right corner — this returns the items to your inventory even if you're far from your body.

Can you specify which mods these features are from? It's most likely a mod conflict with one of these functions, particularly the return items to inventory one since it seems the basis for this duplication glitch occurring.