Stan, in Mixcraft, supposedly you do the following:

"You can already work with the individual channels of a stereo sound. Just right-click on it, select Channels and then choose the channel you want to work with. You could duplicate the same sound on different tracks, select the right channel for one track and left channel for the other or whatever. "

I don't have it myself, but I do haunt their forums. Mixcraft is closest to the marriage I'm looking for between PTPA/RB and Tracktion.