Item Duplication Exploit via item shadowing

It is possible to duplicate any kind of item in vanilla minecraft by using a technique called "item shadowing" (requires update suppression) which got introduced by the Chinese Technical Minecraft community:

https://www.youtube.com/watch?v=mTeYwq7HaEA

And got made popular by eceleb docm77 who did it on Hermitcraft.

And here the way of how to dupe items with it:

https://www.youtube.com/watch?v=XUsbB7Hz8iQ

Thanks to docm popularizing it, it will take a week maximum till we see some people on all servers abusing it.