Item duplication with chests in multiplayer

You can get infinite items in survival multi-player mode if both players select the same item at the EXACT same time. it takes quite a few tries. it basically just duplicates the item both players have selected by putting the one item in both players inventories. they can then proceed to put the items back in the chest and have twice the amount as before. http://www.youtube.com/watch?v=KVW9kXVIeaw this is a video showing the glitch.