Glad to hear the bore is good. That's usually the biggest issue.

As to the markings, this rifle might have been confiscated at some point by a government armory (particularly if it came from Africa) and marked by them. I have 3 type B's that came out of S. Africa with the Mauser serial numbers polished off and a new serial number applied. It could be something like that or it could be the identifying mark of a gun or shooting club or even the owner. If I had to guess, I would say one of the latter. It only adds to the character in my view.