The Dark Savior game disk has a single Redbook Audio track that contains five different songs on it. One of the songs is the normal end credits theme and one is the FMV ending theme. The other three are variations of the ending song that aren't used for anything, including one that is a soft, slow saxophone rendition. Since the game has five parallels, it is plausible that each parallel was originally intended to have its own ending song, but the reason the songs were omitted is unknown.
Source: Flying Omelette