Shift-Clicking on an item when repairing it on the craft table replicates it.
Seems it work with any repairable item (Bow, axe, sword, ect).

Repairing a bow on the craft table with another bow.
I placed my bow and damaged bow from a skeleton to repair them.

Filled empty inventory slots with bows.
I accidentally shift-clicked on the bow to receive the fixed bow and the empty inventory slot filled up will bows.

Steps to Reproduce:
1. Placed damaged item in the craft table.
2. Place another damaged item of the same type of the first.
3. Shift-click on the end item slot on the craft table instead of clicking.