Thanks fragment. That makes sense.
I'll hack my program when I get time, so that it works out the results your way.
Edited to add: Now I've thought about it a bit more, I'm still not sure. Each of those 720 possible ways for the balls to come out is equally likely? My program just runs through all the possibilities and finds which card wins - once a card has won a game, it doesn't care about any remaining numbers. In the card A versus card B example, B wins 384 of the possible games and A only wins 336.