It is only the first "oooooooo... oh... ohhh. ohhh" vocals from Roger that are different. They did not have the original tapes and could not use them for the Audio-DVD. Therefore, they had to take different takes of these vocals. It is interesting to listen to but not that breathtaking.
However, I do find the Audio-DVDs extremely enjoyable. CAn't wait for Day at the Races.
Keep 'em mowing blades sharp!