I’ll listen to it, but (for example) track 14 is clearly for two solo singers only and it makes no sense to list Michael George as bass-baritone and baritone on the same track. Also, the mezzo(/alto?) only sings on the last track. Given that the chorus is the BBC singers, I doubt any of the soloists are doing “backing vocals” on other tracks - this would be rather unusual for oratorio.
Having said that, there may be errors in the track relationships that only listening plus a bit of research will determine, since the soloists are only explicitly credited at the release level on the CD booklet (with implicit credits via their roles on the tracks).
On a slightly separate note there seems to be a bit of confusion over voice types. Wikipedia lists these as Bass, Tenor, Soprano and Alto. The CD cover lists them as Bass-baritone, Tenor, Soprano and Mezzo-soprano, but describes the last role as Alto in the detailed notes. MB shows Michael George as being Bass-baritone for Raphael, but Baritone for Adam. I’ll do a bit more research, but should voice type descriptions in relationships follow the score (where possible) or the home range of the singer?