R.Marshall,
It is not very common to have two scopes for the same rifle, but it is not unheard of either. One of my German hunting friends had a Heym Mod 33 Dural drilling 20/20X 5.6x52R with both a 4X and 6X scope. He used the 4X in the mornings and the 6X in the afternoons, because it was better in the dark. There is also the possibility that your rifle is one of the many that was separated from it's scope at the end of the war and subsequently had another one mounted.
Mike