This bug can duplicate items, like sword,bow,pickaxe,axe,etc.
You need this:
2 Items and nothing else.
How to do it:
Place the 2 items in a crafting table and click shift and the item.
Boooom Your inventory is full of this item.
This is tested in the version 14w05b.
Please do not mark unreleased versions (anything starting with "Future Version") as affected. You don't have access to them yet.
Also a duplicate of MC-46715