[Viking Jonsson]"stereo or mono if it's panned right"
What makes something stereo is the panning. That is like saying it doesn't matter what you set your camera too as long as the settings are right.
If something is recorded as stereo you want to keep it stereo. When you record dialog you are recording that in mono, you would want to leave it mono. For stereo to sound like stereo there has to be differences in the right and left. A gun shot on the right side of the screen, you would only want that sound coming from the right speaker. Music is stereo to give it depth, separation between what you here on the right or left. Listen to 70s rock and you will hear major sweeps cause it was a new thing.
You can use dual mono to boost the audio levels but it will sound the same as a single mono. Dual mono tracks raise the level 4dB.