No, it is much more difficult than cut with one foot and 6/8 with the other, harp. Try it! It is like tapping a very fast waltz with one foot while tapping a reel with the other. (or a waltz with one foot and a very slow reel with the other. In any case the beat is the same and the rythm just differs between feet.)

I think he did the three against two because he could do it, and most people can't--that is as a show piece. In the newsreel of his wedding he does it while playing a snatch of "Goodnight Irene". He doesn't do it as a tap dance but sitting with his legs crossed. You can see him do it.

Murray