A master isolator would affect both channels (assuming he’s running two decks) so your theory is not necessarily correct. Or it could be he made his own edit.
Billy is a definite keeper. The sales history shows the last copy purchased was 2013 (me), before that sold in 2010!! Shit is scarce, but hey, I’ll let you know.
I’ve asked some people, hoping If I get a lead on this track.