Yes. There were other Q in the Q Continuum when Voyager's crew visited it. There were other Q that came to our universe, such as the Q that we call Q2, Q's wife, his son, and Quin.
There was also Q, who was responsible for taking away and restoring Q's powers, and who previously had "misplaced the entire Deltived Asteroid Belt", in the TNG episode "Q Who".
And there was Q, aka Amanda Rogers, in the TNG episode, "True Q".
Finally, it is debated that General Trelaine was a Q in the TOS episode "The Squire Of Gothos".
Actually, Q2 (Corbin Bernsen) and the fact that Q2 "misplaced the entire Deltived asteroid belt" is established in ST:TNG "Deja Q" ProfessorTrek 18:56, August 17, 2011 (UTC)