Yeah, I had/have two laserdiscs of My Fair Lady: the original widescreen release which featured a very faded print, and the big box anniversary edition with its Ascot design motif and the restored edition of the movie.
The keys were taken down for Audrey already. And when it was clear they needed Marni to sing almost all of the score, she sang them in Audrey's lowered keys, not actually the most suitable for her much higher voice.
It was Jackie Ward who also dubbed for Natalie in Inside Daisy Clover. The soundtrack CD of Inside Daisy Clover has all of Natalie's attempts at singing the songs in the film (along with a terrific song that got cut). They were right to dub her, but I do love hearing her try.