Wow, hadn't noticed that, but I think you're right. I think it would be very easy to get them confused...I think she did a good job of playing the spoiled little brat that Belinda ended up becoming after so much attention. And then, later in the book, she ended up with faded looks and a dowdy figure. Serves her right, I suppose, huh?
And Rupert Everet looks so great in this movie. He has aged magnificently.
I have owned the movie for a long time, but I just recently watched it again and I saw THE SAME similarities you are talking about! I am so happy you posted your message because I thought I may be "seeing" things... Even the way tehy talk is similar! They should be casted in a movie together now that the american lives in London!