The AntsCanada Ant Forum's

Are these ant's polygynous so I can keep multiple queens together?

no. some queens can get along for a short period of time and then kill each other when the workers arrive. camponotus are not like this all camponotus that i have put together attack immediately.

I've heard that Camponotus subbarbatus is one species that uses pleometrosis, where multiple queens may get together to start a colony, but then fight each other until one survives. It's safe to say that C. subbarbatus is simply a one-queen or monogynous ant species.
Besides, since you might be raising multiple queens in a healthy, safe, indoor environment, it's best to let each queen raise a colony by itself so you can enjoy more ants
(I think pleometrosis is one way that queens ensure the initial survival of a colony, since *starting* one is the hardest stage in the wild)