On my XP-60 I have created a User Performance with the patches that I need, and set it to Single, as opposed to Layer. When I am recording track one, I can hear the selected patch, but when I play it back it plays several patches together. I had intended to use different sounds on different tracks (I thought that was the whole point).

How do I tell it to play back only the selected patch? Or is my machine faulty?

Your unit is probably not faulty, you may just need to redo some settings.

If your sequencer is playing back more than one patch, then you probably have several tracks set to the same MIDI channel. Check and make sure every track is set to a different channel.

See if that works.