if the runtimes and all that are the same, it wouldn't be difficult or very time consuming to do this with FFMPEG or even MKVTOOLNIX. I'm obsessed with comment

if the runtimes and all that are the same, it wouldn't be difficult or very time consuming to do this with FFMPEG or even MKVTOOLNIX. I'm obsessed with commentary tracks for movies and television -- and rarely does one copy have everything in one realistic-to-archive file size. Typically the offset between the two sources will be identical (assuming their respective sources are also consistent), which makes the entire process a breeze.