Grem
sharke, I checked when I got home. I can clone audio tracks and none of them display the behavior you say happens when you clone a soft synth. (I forgot to try that. But I will if you need tomorrow.) I had a guitar trak with info on it and fx in PC and stuff, and I cloned 4 instances. I hit the mute button on all of them one at a time and the only mute button that comes on was the one I would turn on. Same with Solo button.
Gotta get some sleep.
To be clear, the grouping happens when you clone a MIDI track. When you insert a synth with a MIDI/audio output pair, the MIDI track's solo/mute buttons are grouped with the audio track. This makes sense, because you created them to work together as a pair. But when you clone the MIDI track, you also clone it's grouping with the audio track. They could of course create a "duplicate track" function, but that would make no sense unless it was possible to select "no output" for a MIDI track. If its output is to the original synth, then it might as well be grouped with the synth track.
So I guess what I want ideally is the option to duplicate a MIDI track along with all of its settings, but for it to have no output. For now, jb101's solution to clone the track and then archive it works well.