Duping exploit

In the latest patch of Minecraft there is a duping exploit. 

How to reproduce(i had done it unintentionally):

If you wait the right amount of time for an auto save to happen in your world, place at that exact moment some shulker boxes and then restarting the game (alt-f4 or close software on switch) you will have those shulker boxes in your inventory and placed down too, effectually duplicating them