Hopper Clock Duplicates Items

When you place two hoppers feeding into each other to create a clock, the item in the hopper can sometimes be duped freezing the hopper clock and causing the redstone comparator to freeze in the on state. HopperClocks can be less buggy usually when unloading and reloading chunks, but this causes the use of hopper clocks to be even worse then a redstone clock. Anyone else have this issue?