Bug in crafting: Multiply items easily

I found out how to easily multiply items through crafting in beta 1.2.0.22. How it works: Put items to one empty slot of crafting screen. Then click one empty slot and then the slot where your items are and you can see that they are doubled. And that works always, so it's possible to get unlimited amount of resources through this.

I was playing survival mode on Samsung Galaxy tab A.