Because metaclasses are classes, yes, classes whose instances are metaclasses are also classes whose instances are classes and thus are also metaclasses. But you could distinguish this subset of metaclasses as “metametaclasses” if you wanted to, to distinguish them from more general metaclasses just as metaclasses are distinguished from more general classes.

But AFAIK no one has come up with a distinct application for custom metametaclasses which would make having terminology to discuss them necessary or useful other than for entertainment.