Duplication glitch with items that have a durability is made by repairing items.

Put the summary of the bug you're having here

What I expected to happen was...:
My items would repair

What actually happened was...:
Pickaxes for days

Steps to Reproduce:
1. Have 2 of the same items with a durability.
2. Repair the items
3. Done

Video link: http://www.youtube.com/watch?v=vgkD2nP3nPI&list=PLT1BWZ3S_EhQOREWL4tmS75osA_p0UKNO&feature=mh_lolz