Duplication bug. Dupes ANY item(s), up to 15 spaces of items per time.

Put the summary of the bug you're having here

knocking a donkey or mule's life down to half of heart, when they're wearing a loaded chest, then puch them through a nether portal with a piece of cactus RIGHT outside of it on the nether side.

Since those 2 mobs have a 2x2 hitbox, the cactus kills them and the chest contents are doubled & sent back through the portal to the overworld where you are still standing.

Steps to Reproduce:
1. Load a donkey or mule up with (up to) 15 inventory slots
2. ...Hit it with a poison 2 splash
3. ...ride it to where you and it are inside the nether portal (with the cactus on a piece of sand right outside the portal on the nether side, then get off the donkey/mule & walk back,

I just want to add that the infamous "cactus dupe" has been a meme for a long time, but this is legit. Im also the one that discovered the kick glitch in Nov. of last year, & I literally tried doing this with EVERYTHING but cactus first, even magma blocks, & cactus is the only thing that sends the items back duplicated