Audio track turning from stereo to mono

In the Edit page put a video with 2 or more mono tracks on the timeline, add a new stereo track on the timeline and put a stereo clip on this stereo track, now remove the mono clips from the mono track.
You now have empty tracks. Right click and select remove empty tracks. The stereo track moves up to where the first mono track used to be and turns into a mono track.
You now have empty tracks. Right click and select remove empty tracks. The stereo track moves up to where the first mono track used to be and turns into a mono track.