You can submit as many as you like! From the Jam overview:
Use as many or as few of the MIDI files as you like (minimum of one (1), for obvious reasons) . If you only want to submit a single track, that's fine. If you want to go the whole hog and submit an entire suite, that's fine too.
I would recommend using something like Scritch to embed a player in your product page if creating a suite! (I should probably add that to the jam page!)