Add Channel (Mono/Stereo) Fixing Support
If the audio was recorded in Mono, you should be able to duplicate it and make it (faked) Stereo. If the audio was record in Stereo but only in on channel, the channels should be able to be duplicated to be Left & Right, not just stuck in one channel.

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Matthew Woodget commented
Here's another scenario: Filming with a mono lavalier mic results in the speaker audio being left channel only. It would be great to easily duplicate the left (or right) channel into both channels resulting in the mono audio playing through both left and right speakers.
In Premiere Pro you can use the "Audio Channel" setting on the right-click menu to force the audio track to be 'left only' which puts the audio in both channels. It would be great if this was in Rush for quick fixes on those 'rushed' videos.
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My Name is James commented
These are audio channels I'd like to fix, one is Mono that I would like to make Stereo while the other is an accidental Left channel recording that I'd like to duplicate to make Stereo.
Thank you.