End portal duplication.

1.13.2 Duplication glitch while a mob such as Donkey/Llama die at the exact time while going through an End portal. Everything inside the saddle bags are dropped as items in the overworld, whilst in the end a duplicate of the mob that died in the overworld.
This may have been patched in 1.14 or this bug report may have been made already as far as i can see.

Here's a few pictures of a setup we are using.