I believe so. Digging through some disks...digging some more....and
yet more...ah, found it, knew I didn't imagine it! It's a small Integer
BASIC
program called "Four Voice Music - Apple version by D. Kemp". Comes with a
couple of demo song samples (Star Spangled Banner, Exodus theme, Deck the
Halls, Dance of the Reed Flutes and Blues on the Downbeat).
It sounds very similar to Electric Duet, only it seems to double up on
the existing two voices, as if more harmonized and fuller (rather like
playing chords on a piano versus pressing one key). If you'd like a copy
I can send over a copy of the disk containing it, SHK'ed or 2MG'ed.