I wondered if they could be Masters but I don't know how we could tell.
We could start a thread asking about the range of Master's seams or Master's translucent bases or Master's UV reaction ... but unless we have folks looking at original packaging that might not be very informative.
Most of what we think about Akro versus Master has been passed down like an oral tradition among collectors. Our IDs are made based on that tradition and the ID's reinforce themselves.
Long seam for Akro. Short seam for Master.
UV-reaction for Akros. Not UV-reaction for Master.
So if I start a thread for Akro patches and a thread for Master patches, people might sort them by stereotypes, and I'm betting a lot of marbles would end up in the wrong thread, with errors going both ways. It could turn out that if we had a bunch of Master's boxes we could find a lot of marbles with traits that we have been identifying as Akro. And there are surely some Akros I've been calling Master.