Ok...you have to cut these music cues into stereo tracks. When they look at the old cuts that have cues, and match back to them, they match back and are stereo cues (because of the hard work done by the AE's). So now the have stereo cues that they can cut into stereo tracks.
IF they happen to match back to clips that aren't stereo yet (somehow skipped), then all they need to do is modify that cue to be stereo.
If they want to load the sequence into the SOURCE monitor to get the music, or if they select the cue and load it into the clipboard, they'll be dual mono. So they shouldn't do that...they should instead match frame to get the stereo cue.