Sorry , video editing is not my playground. But here some suggestions: Prob: first you have to seperate the video from sound, then processing the sound and afterwards join them again absolut synchronous. Solution: My way to solve (rare) problems like this is first to browse all my cd's out of my subscribded PC Magazine, then freeware sites and then try to find my luck by installing and try /error working. It's the die hard way but training at it's best. Or I hope a video expert is passing by with the right answer. (unlikely because no 'video' in subject)
At least the only hint of value I can give to you: It seems to me you have a recorded multi language broadcast. Our stations often send the translated language(of a movie) on the left channel and the original on the right so you can choose. We often set left ch mono as default because if suddenly a multilanguage movie starts you get both at the same time if the setting is stereo.(sounds aweful) So if you don't remind this before you start your recording...
Sorry that I can't do more for you
Andy