It is possible to doublicate every Item in Minecraft!

It is possible to duplicate every Item in Minecraft with the new crafting-help Tool in the Inventory!
This Bug can also be recreated in Minecraft Singleplayer, but it is a huge Bug in Minecraft and extreme critical for everyone who is playing with the 1.12!
This Video explains how this bug works:
https://www.youtube.com/watch?v=qQwraXFTaB0