Duplicating a mono track does not make it stereo. It makes dual mono and will not sound any different than a single mono track(except louder when the 2 identical signals combine). Its still down to the question about what the goal is? Some general stuff to consider"
1-a mono SOURCE(like a bass guitar, snare drum or a vocal) is a mono signal, and belongs on a mono track.
2-there are a few ways to create a stereo-sound(not real stereo, but an effect) from a mono track, such as using a mono/stereo reverb/delay/chorus plugin(whether this is good or bad is totally up to the listener)
3-down to the most basic( I have no idea of your skill/knowledge level and no offense is ever intended
); its perfectly normal to use many(or even all) mono audio tracks in a recording, and use pan controls to spread things across the stereo sound field. Once again, the source dictates whether the recording should be mono or stereo
4-another way to give "space" or "spread" to a mono track is to pan it to one side and send(using a send) to a mono AUX track with a mono reverb, panning the reverb to the opposite side.
If you describe the desired result, I'm sure you'll get multiple ideas on how to get there
