I remember a movie about two twins one sung opera and I think one played and a chello. It was a movie where one of the twins sing a tune from a lost Dutch composer and dies on the stage and for the life of me I cannot remember the movie. I think it was something like renata renarta

That reminds me of Hilary and Jackie
The tragic story of world renowned classic cellist Jacqueline du Pré, as told from the point of view of her sister, flautist Hilary du Pré-Finzi.
Hilary and Jackie (1998) - IMDb

http://en.wikipedia.org/wiki/Hilary_and_Jackie