Mono

Most audio you listen to is available in “stereo”; this means different things are played between both the left and right speakers. However, you can have your PC mix your audio to mono, combining everything on both speakers.

This will allow you to use only one headphone on your PC, but still listen to both left and right audio tracks. It's also very helpful if you have trouble hearing in one ear. The mono audio option was introduced in Windows 10's Creative Update, so it's just like iPhone and Android.

How to Make Mono Stereo?

Select all material from one channel and copy it to another. This method is not suitable because the result is repetition and even the appearance of the chorus effect causing distortion is not ignored. In such a case, it makes sense to process each channel with an equalizer to cut off or add certain frequencies that might overlap. 

Therefore, in some applications (for example, in the Audacity editor), you can use built-in tools such as Split stereo track and Make stereo track, as a result of which you will get a two-channel sound.

However, nowadays mono tracks are usually recorded in such a way that programs sound the same on both channels. For example, you can put the same material on different tracks, and then “move” one of the tracks a bit, to get a stereo effect, for example in Cool Edit Pro (currently Adobe Audition), in multitrack mode.

To do this, you must first distribute the tracks around the panorama 100% (one all the way to the left, the other all the way to the right), then increase the horizontal zoom (scale) and pan a track along the time scale (by panning, by ear).

For more information about music videos;

https://cinema8.com/blog/how-to-choose-the-best-music-for-your-videos