I had a copy where the rotation speeds are different. One is fast and the other slow. To see that I'm right, I bought another copy and I got the same result and that this 'new' used copy had a pitch difference in the music (yes, I used the same battery as in the old one.) The only other thing is that I have not replaced and try the games with new batteries.
Dose anyone's game have the same or different speeds? This means a lot because clearly one side has a advantage when playing the game.