Item Duplication Glitch 0.12.1

Item duplication glitch on Minecraft PE 0.12.1 beta

How to reproduce(sorry for my bad english)
1.Go to the nether
2.Throw an item in the portal(example:2 diamonds)
3.Return to overworld and collect the 2 diamonds previously dropped
4.Go to main menu,reload the world
5.Now you can see other 2 diamonds in the portal,then collect it,so you will have 4 diamonds in the inventory