NYSR
I am not following what you are saying. The master fader is still behaving like the master fader. It controls the output entirely even though not assigned to anything. And the signal is received at the mixer on channels 1 & 2.

There are several places in Sonar where you may see a label for "master". It sounds like you are not looking at the "Mains" channel strip. The "Mains" is automatically inserted for each available audio card output. The meters and sliders on the Mains actually control what is going from Sonar into your audio interface, and it is that signal which is going to be exported. It can be recognized as a channel strip by default at the extreme right in the console view, the word "master" appears about half way down, and below that are a mute button for each channel of output, between which is  a padlock icon to lock the sliders together then meters and slicers. Look at page 530 of SONAR_X2_Reference_Guide.pdf under the section "Track Inspector Overview."
 
It may be possible to set your sound card as the output from another track or bus, but that is a bad idea, as it bypasses the mains. You would be able to hear it, but what you hear would not be what you will be exporting. Best practice is to be sure that your sound card never appears as an output anywhere in Sonar.

Thanks for the various suggestions.

Upon close inspection (my eyesight is not that good anymore with a computer screen) I began thinking about what Kenn said because other than a weird driver issue something like what he suggested just had to be going on. Sure enough, the Master fader ALSO had an active send assigned to the stereo pair 1&2. That, of course forced that fader to send its signal out twice to the exact same destination; once through the output and then again through the send which explains how when it was unassigned it was still sending. I deleted the send and THAT problem is now solved. I feel a little foolish. I do not remember adding a send to that main but evidently I must have at some point in time.

Thanks, Kenn.

I will now try an export to see if that problem is also now solved.

Thanks to all here and elsewhere. It appears all problems are now resolved.

Glad I could help a fellow upstate New Yorker!