Duplicate an audio track to have 2 tracks of the same audio

I recorded a video of me speaking with an external microphone. I want to have it on another track exactly the same audio, so that you can hear on left and right side speakers/headphones.

How would I duplicate the audio track?

Thank you.
Guiseppe

Create an audio track on the timeline (Ctrl+U) and dag a copy of the video file there.