Item Duplication Bug

If you setup a hopper clock, two hoppers facing each other. Drop 10 items in it, and come back in a few days. You'll have more then 10 items in the hopper.

This makes hopper clocks extremely unreliable in server configuration.

Would be nice if there was a command block timer option. Would use scoreboards but they need specific player to be online so it's hard run based on it.