Does uniqueness matter at all for different versions ? Like if I use Cadmus Labs with a Superman-Red out, can I then recruit another Superman-Red ?

Absolutely.

On a side note: One you pay Red's 1 Endurance or activate Cadmus Labs, your opponent must do something about then and there to have it matter.

I point this out because once I activated Cadmus so I could recruit Superman:Kal-El without losing Clark Kent or Red. As soon as I put Kal-El on the table, my opponent tried to blow up Cadmus with Have a Blast to KO my other two Supermans. It doesn't work that way, though. And I still got to keep my Supermen.

I just wanted warn everyone about that. Don't let it happen to you.