Item duplication durring repair

while attempting to repair items by combining in the inventory crafting box(4x4)
I placed two swords in the crafting box and when I removed to the repaired item, the two original source items remained.

I tested this with swords and picks bot diamond and stone.

Steps to Reproduce:
1. have two items of the same type that can be repaired by combining.

2. Open your inventory and place the items in the 4x4 crafting grid

3. remove the repaired item - both source items remain.