Promoting a Pawn

I never knew that you could have two queens at the same time. I'm playing a game at the moment where I have a very good chance of winning my opposing player has already got a queen and just about to promote a pawn which I could have taken earlier, which I hesitated thinking it would only be promoted to a piece they have lost. Now my opposing player has got two queens on the board at once. I have never seen this or ever played a game like this. Could somebody tell me if this is normal and happens in real chess.