read the liner notes - perhaps they explanied it there - i have not read the liner notes myself though i have the album
one of the reasons could be that they have shipped the tapes from one area to another and it got lost during the shipment
it has happened for a danish film made in the 50's. there was made an alternate version for the US public - the film was shipped to the US and got lost. It was asembled for the dvd release with only songs and some few bits of dialogue surviving. They had to fill in the rest of the dialogue with the danish dialogue (which have resulted in the film looking as a film that have been synchronised like the french and german versions of US films).