The 1st one is an aftermarket item. But the 2nd one . . . ah, we can only hope.
According to Stephen Dorsey's "American Military Belts and Related Equipments" That appears to be the Model 1880 plate, the 1st and rarest of the "H" plates. It is described as "A two piece sand cast plate, with a raised US on an oval recess. All raised features were polished after casting." The accompanying picture matchs your plate.
It would take an hands on expert to determine if it is the actual item, but it surely looks like it.