HDuaneaz said
I would like to learn how to mix it like that, maybe play a duet with myself.

If you are just making audio, you can do it with a computer running Audacity (free software), an earphone or headset to hear a metronome or click track, and a cheap microphone on an extension cord.

It's not that hard to learn.

You could even play a violin part and cut the pitch in half so you can use violin to create a track that sounds more like a cello.