This package includes both first and second alto chorus (given in most of the vocal scores as 'Soprano 2', as is standard 19th-century practice). As often happens, a lot of the time they are the same anyway, so the price is based on just one part.
The recording follows the Schirmer vocal score (basically the same as most other late-19th/early-20th century scores). There is a separate file for the act 2 finale following the Schott vocal score, which has some differences from other scores in circulation.