PortalDupeBegone Mod 1.12.2
MODPatches an issue where entities can go through portals but take a tick of damage at the same exact time, causing them to both drop their items, and show up alive on the other side of the portal with a second set of items.
Patches an issue where entities can go through portals but take a tick of damage at the same exact time, causing them to both drop their items, and show up alive on the other side of the portal with a second set of items.
I believe this behavior to be patched in Vanilla 1.12.2, but it appears that some mods can cause the behavior to reappear.