You
may sometimes find it useful to use a mono audio clip as a stereo
clip. Using the Source Channel Mappings feature, you can apply a
mono clip to a pair of left and right stereo channels.
In the Source Channel Mappings dialog box, select Mono
As Stereo.
Important: You can apply the Source Channel
Mappings command to a mono clip only in the Project panel, before
the clip appears in the Timeline panel. You can’t convert a clip
instance to stereo when it’s used in a mono audio track.