Player Joshinja has revealed a new duplication glitch that has come up in Minecraft 1.8.3.You can subscribe to him on YouTube here.
For this trick to work, you need a chest, TNT, and a nearby dropper. You will also need to already have multiples for the item you want to duplicate. To start, place the chest and TNT next to each other. Then, place the item in the chest.
You then toggle the item between the chest and your inventory, Joshinja suggests you bind one key for this purpose. Of course, the chest will eventually explode from the TNT.
You repeat this over and over until your inventory shows said item is zero. Hopefully, you should still see the item in front of you in case it doesn’t work. Go to the dropper, place one of the items in, and start duplicating.
Fans chiming on this reddit point out that the bug has been around for a while, and more interestingly, Mojang has no interest in touching it.
