Audio mixing

I searched around a bit and couldnt find a good answer so my first question post here: (not sure if this is the best place or not but oh well…)

I have been building dvds of old mono vhs tapes. now that i am pretty much done i have noticed that due to my capture setup (fixed now) a few of these dvds are encoded in stereo with the one audio stream moving between the left channel and the right channel every 10 seconds or so. could someone reccommend a good program to mix the two audio channels? i am using eaither dvds directly or mpeg2s as the source.


edit: i have been using nerovision express 3 as my dvd authoring package (mostly because it came with my drive)