if you use two recorders to record the same show, you will always have differences in the recording's pace. even if you used two of the same recorders to record one show, you will get both recordings at different speed, I suppose. it's usually just a few milliseconds and can be adjusted in post production with a professsional audio software. Mixing two sources always sucks the big one, that's why I hate doing it, and barely do 2 recordings of the same show.