"Also, someone else might wish to use a good piece of music for a
different dance, on occasion, but won't be able to if it has two chords."
Good point. In fact, I quite often use a recording that I know has nice
tunes on it for teaching a dance that doesn't come with its own music, or where
I don't possess the right music. And it's very irritating to discover in
class that every time I restart the music, there are two wretched chords. Of
course, you can say that I should have listened to the recording beforehand,
but I'll admit I don't always do that if I think I know what's on the CD.
So - for the purpose of your CD - I would join those favouring one chord.