Items get stuck in crafting grid

 Steps to Reproduce:

1. Game mode creative
2. Tap a stack from creative inventory into crafting grid
3. Tap another stack of the same item type in the same (currently occupied) crafting grid slot

Observed Result:
The item is entirely stuck in that slot 

Expected Result:

Trying to put two of the same item in the same slot dose nothing
(dose as it visually appears at first