It's worth pointing out that a bunch of these Hitchcock films aren't really owned by Universal, but by the Alfred Hitchcock estate, thanks to a deal he made with Paramount in the 1950s. Universal merely negotiated a distribution agreement for them with his daughter in the 1980s. That deal took many years to complete.
I just watched FRENZY yesterday. I would love to hear what Mancini composed and know why it was rejected. A few parts of Goodwin's score did fit the visuals, especially the creepy, dangerous music. However, I was flummoxed by the main title that seemed very upbeat and positive. It also played in other parts. It seemed like it was used to show off or highlight the bustling city of London, but it seemed way too positive for such a dark picture. (IMHO.) For me, his music didn't marry the tone of the movie.