convert stereo track in two mono tracks in timeline

can i convert a stereo track in two mono tracks in the timeline?

background and workflow: i have a 5 track file from MixPre3. after right clicking on the file, then chosing "clip attributes" i delete the L and R track - also track nr 5. the remaining tracks 3 and 4 will be used. FORMAT is set to MONO.

if i then drag the audio clip to the timeline directly i get two seperate monotracks as expected.
but i work on multicam. therefore i select the audio file and the video files, create new multicam clip and the resulting multicam has the audio as a stereo clip.
the settings in Preferences/User/editing/new timeline are set to Audio MONO

any help on this one?
THX!