Okay, I have a soft synth I want to use in the piece I'm working on, and I want to use it for two parts, each part with a different patch. Unfortunately this synth is monophonic only, so with no multitymbral capabilities at all. So that's why I've loaded two of 'em. But to differentiate the two, I've assigned each to a separate midi track, which corresponds to the voices I want to use. That is, I've indicated the track and the voice I want to use with each instance of the synth itself. I don't know if this explanation is confusing or not. What I mean is, each space in the console view that corresponds to a separate instance of the same synth has been set up for a separate MIDI channel and patch. And each of these channels and patches is represented by an instrument in the tune.
 
But all this gets ignored. The two parts end up getting combined with a single instance of the synth, with predictable results when you have a monophonic instrument.
 
So I guess what I'm wondering is, is it likely that some synths are gonna ignore the separate channels and patches being indicated and just combine into one single-voiced instance of the synth despite the efforts being done to keep each instance separate from the other? And which follows, should I just bite the bullet and use a completely different synth for one of the parts? I'm leaning toward this. It's not worth the hassle anymore. But I'd still like to know if there's anything I overlooked when I tried to separate the two instances.
 

It is not clear what you are doing with the audio tracks or whether you are using a MIDI controller. You need to have two audio tracks as well as two MIDI tacks. If output of MIDI track 1 is instance 1 of the synth and input audio track 1 is instance 1 of the synth, and output of MIDI track 2 is instance 2 of the synth and input audio track 2 is instance 2 of the synth then you should be able to get two audio tracks recording what you want. If you are using a controller, then the possibility exists that it is being received by both MIDI tracks if they are on the same channel or Omni. If your synth has its own MIDI out, then that should be disabled to prevent the MIDI from being echoed through one instance to the other.

You set the output of any midi track to the synth you want, you don't need different channels to do that. 
When you insert 2 of the same synths it's a good idea to use track colors so you will identify them easily. 
They will have different numbers beside them. Here I have 3 instances of Strum session. 

Guys, obviously I had overlooked something, which usually is what happens with me and Sonar. I had gone ahead and removed one instance of the synth, then went on a quest for a close replacement in my unnecessarily large collection of VSTi's.  I found one, too, and was in the process of setting it up when I checked back in here. Well, I decided to give it a go once more, and loaded a second instance of the synth, then set it up to use that single MIDI track, and whaddya know! It worked. I think possibly where I messed up -- not really sure, but it seems likely -- was failing to indicate the second synth in the Output popup of the second instrument's track. I've forgotten to set things there before and I wouldn't be surprised if that was what I did this time. At any rate, it was kinda worth it because I got to go through a bunch of VSTi's that I don't normally use, and got reacquainted with a couple useful ones and sort of discovered for the first time the usefulness of a couple of others. So this quest wasn't in vain.
 
As always, thanks so much for -- in this case -- just double checking my work.