Recording live show... advice?

[64Guitars]

If you've only recorded on one track, then you could set the pan of that track to C00 (centre) before mastering. This will send that track to both channels.

However, there isn't any point in exporting to a stereo MP3 or WAV file if both channels will be the same. So you should specify a single track for the mastering destination instead of a pair of tracks (see page 76, step 2 of the Micro BR manual). Exporting should then produce a mono MP3 or WAV file which will be smaller and will play through both channels of a stereo sound system.