If you want the right channel to be output to left and right channels, right-click on the audio and choose Channels>Right only.

Gary

You obviously won't have "true" stereo regardless...only the right side playing through both speakers.

...so you might as well choose to combine the two into a mono track (unless there is noise on the bad track).

One FX that exists in Sound Forge but not in Vegas, is a channel converter that will create a stereo feel from a mono track. Not very convincing alone, it is still very useful on single tracks that are to be mixed with others. You can experiment with duplicating tracks and applying fake stereo (with different settings, mind you) to all of them.
Tor

You can also tweak the EQ to emphasize, for example, the bass in one channel and the treble in another.

I use this technique sometimes if I'm shooting a band, but only have a mono microphone.

C'mon, Zip, you asked the exact opposite of this last week. Same procedure, only in reverse. Right click, select either Right only, or select mono.
If you want to make it 'sound' stereo, you can zoom in tight, move one channel by a couple hundredths of a second, and apply a compressor to both channels. It will be a pseudo stereo, but not horribly convincing.