So far, all the clips (RT and RD) that I have dragged to Sonar are in stereo, which perhaps does not mean that the instrument was actually recorded in stereo. Could it be that BIAB defaults to rendering in stereo, regardless of whether that particular RealTrack was actually recorded in stereo? Anyone know? Or, if it renders to stereo, does that mean it is a stereo RT or RD?

Are some of the RD also recorded in stereo, and others mono?

Especially if the track being used was recorded mono, then there is no need to keep the rendered clip in stereo, identical on both sides.

If the original track was recorded in stereo, i'm not sure how many people would hear the difference, to keep the instrument in stereo, or bounce to mono? How many of you hear that difference, with a single instrument?

If however, the stereo recording pans the instrument for a particular setup in an ensemble, that would be something different. I doubt that is the case though. (Please correct me if it is the case.)