They were too busy working the audience to give them tips to play requested songs. They calmly took turns and certainly were not competing with each other.
The piano players did not duel whatsoever. It was supposed to be humorous and there was nothing funny about the show. The advertisement oversold the actual show. We are big fans of stand up comedy shows so we immediately looked up the Comedy Club line up when we decided to visit Foxwoods, but this Dueling Pianos show was playing.