Version Information

Minecraft: 1.12.2
Forge: 14.23.5.2814
Iron Chests: 1.12.2-7.0.59.842

Report Information

i have no idea on how to reproduce the issue but basically one of my players was just trying to move their shulker box and it crash he then mention that it dupe the shulker box

EDIT: after looking to the issue a bit more it seem that the player was using Thaumcraft focus plan and dislocation to move the shulkerbox but it seem that he had place an item inside of it before he moved it im unsure what that item is.

Steps to Reproduce

Crash Log

https://pastebin.com/raw/LUWVF6Bm

Forge Log