Exploit to duplicate items - uses game crashing when you go through a portal with pets

If a player goes through a nether portal after sitting up your dog or cat the game crashes. This can be used to duplicate items.
Immediately after opening the game, put items in a barrel, sit up pets and jump into a nether portal.
The game will crash and when you re-enter you will have traveled back in time to before you put the items in the barrel. The items will still be in your inventory, but when you look in the barrel the items will also be in there.
They can be taken out and used as normal, they will not disappear.

I had to try this several times to get the same results but I eventually did.
I took a video of the glitch that better illustrates it here: https://youtu.be/N56qTHhNHck

Thanks Minecraft bug fixers. Good luck.