Duplication bug SMP

I've noticed a duplication bug in SMP where if I build a redstone clock with repeaters, and link a dispenser up to it, the item in the centre square duplicates if you put an item in it. It only works in the centre square and it duplicates anything I think, even tools. Just wanted to let fellow minecrafters know about it and either use it to their advantage or report it or something, but just letting you guys know. It only works in SMP. I'll add some images soon.