Bukkit

What steps will reproduce the problem?
0. Have 1 stack of something
1. Fill a crafting table 3x3 with in each slot 2 item
2. Put the rest of the stack in your hand slot
3. pick the stack back up and fill 2-3 slots up with an extra 1-2 items
4. put the rest of the stack back in your hand slot
5. Start messing around with the items in the crafting GUI (moving them, dragging them, etc.)
6. do this for around 20 sec
7. Shift left click everything back in the your hotbar in the rest of the stack.
8. See more then one 64 items of what you have

Wich logger the error comes from ?
No error, just dupes

What is the expected output? What do you see instead?
Duped items

What version of the product are you using?
1.7.2

Do you have an error log of what happened?
no

Please provide any additional information below.
Playing on FTB ultimate