In which song(s) do you think vocals were re-recorded? I am curious to know.
The main one is Jerusalem, the opening lines are a different performance, up until "And did the Countenance Divine,"
I read an article somewhere at the time they were producing the 5.1 mixes that some parts were being touched up.
The first time I listened to the DVD slight variations caught my ear in various tracks. Now that I am used to it it has become a blur,
but definitely the opening lines are noticeable for phrasing and pitch.