What is Alice Cullen's name?
Her full name is Mary Alice Brandon Cullen. Brandon was her last name as a human. The actress that portrayed her in the movie was Ashley Greene.
Rosalie's real name is Rosalie. I think you mean Alice. Alice's real name is Mary. Her middle name is Alice and her last name (as a human) is Brandon. Mary Alice Brandon. When she married Jasper, it became Mary Alice Brandon Cullen. But she still goes by Alice. Rosalie Cullen's real name was Rosalie Lillian Cullen (this is on the biography on Twilight Lexicon.com).
Jasper's last name was originally Whitlock but he changed it when he joined the Cullens with Alice. Jasper uses whatever last name matches the current cover story being used by the Cullens. In Forks, he and Rosalie are pretending to be twins and foster children of the Cullens, so it makes sense that their last name would be the same and not Cullen.