I had not used GS for a while, and when I recently fired it up, regardless of what channel I set my controller to, everything was also sent to MIDI channel 1. If I set the controller to MIDI channel 2, the event would fire on GS channels 2 and 1. If I set my controller to MIDI 3, GS responds on 3 and 1. GS channel one sems to be the only channel affected. If I load instruments to channels 2-whatever, everything is fine. I think I will make a MIDI recording, and examine the data to see if my controller is actually sending data on two channels simultaneously (but I do not think it can do that).