Usable items with "0 Uses" should be used only once
With Morrowind Rebirth's main plugin loaded, outside of the smith shop in Caldera there's an apprentice repair hammer with "0 Uses" on top of an anvil.
In the vanilla engine the hammer can be used only once. But in OpenMW (0.46 and the nightlies) it can be used 21 times, the first time you use the hammer the "Uses 0" in self-repair menu change to "Uses 20".
I haven't checked if this applies to lockpicks...etc.