Pardon my ignorance but what does 'over/under. 2' mean?
An over/under has two barrels, one on top of the other. There is a hinged break just aft of the action that allows you to load shells. You can’t load more than two.
All over/under shotguns have a capacity of two.
It is a double barreled shotgun with one barrel over the other.
They either have 2 triggers or a switchable trigger mechanism.
They brake over in the middle to load. They are basically a 2 barrel single shot gun.