That possibility crossed my mind, and it's pretty beat up so it's kind of hard to tell for sure. But I am not seeing the cut-off I would normally associate with an MFC slag so I'll stick with Navarre for now.
These appear to be slags (white striping glass in a transparent clear or colored base glass). They appear to be Akros, IMO. The red one is very nice - Akro called that type Cardinal Red.
I assume you are looking for an ID since we're in the ID section?
They hand made German marbles cut from a cane. The first is a divided ribbon core swirl and the second is a white latticino core swirl.