I'm pretty sure you can. I don't remember where, but I remember coming across options to convert a track from mono to stereo.

Unless you mean recording in stereo, in which case that has more to do with your input device than audacity. (unfortunately putting two microphones in a splitter doesn't accomplish this. )

[edit] Hmm, in the track menu there's an option to convert a stereo track to mono, but not the other way around. There is the option to add a stereo track, though. I have to imagine inserting a mono file into a stereo track might accomplish converting, but I'm not sure.
I know converting channels in wavepad is much more straightforward (there's a convert channels option in the file menu). Unfortunately wavepad tends to scramble the first half second or so of the audio in the process (and sometimes wrecks the whole thing--I've gotten to where I always copy a clip to the clipboard before changing the channels / sample rate because of how often wavepad corrupts the results).
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hi everyone,
Thanks for your help. I'll try things and see if they work.
Best regards lauren