If all you want is separate control over levels, use the mix6to2 plug found under “surround”. Then change the panning type to Stereo dual panner (or stereo combined.)
But if you need autonomous channel control over L&R :
- Solo the stereo track
- EXPORT split tracks directly into the pool and to new tracks.
- Remove the interleaved version from the arrange page and deal with file management when you do your back up.
It’s pretty quick if you do it that way.