I always took this to mean that at any given time there were only 2 Sith as bizarre as that would sound. Now I think I may have been in error. Does this dialog imply that there are hundreds if not thousands of Sith but they only exist in groups of 2? I guess that would be similar to the Jedi in that each Master can only take on 1 apprentice.MACE WINDU : There is no doubt. The mysterious warrior was a Sith.
YODA : Always two there are....no more...no less. A master and an
MACE WINDU : But which one was destroyed, the master or the apprentice?