How to play one-channel audio in both headphones?

I would like to have exactly the opposite of this question, or this . Some audio documentaries on youtube that I want to listen to with an old-style (wired, non-bluetooth) headset have only one channel audio. That is, I hear audio in just one ear. Is there a way to hear the sound in both headphones while playing that? (That would improve the experience, the voices are not always clear, etc.) — I mean, maybe there is an app that has a setting for that. **NOTA BENE**: --- I am referring to **wire** headphones here, **not** bluetooth. The device is Xiaomi A2 phone running Android 10. --- EDIT after comments: Opening the audio file in Audacity, I see this: Although Mediainfo says 2 channels: