Another interesting list -

The following actors were nominated for an Oscar for playing someone who was nominated for an Oscar (either a real-life figure or a fictional character):

Daniel Massey was nominated for "Star!" in which he played nominated screenwriter (and playwright) Noel Coward.

Jane Fonda was nominated for "Julia" in 1977 for playing Lilian Hellman who was nominated for adapting her own play "The Little Foxes" in 1941.

Leonardo DiCaprio was nominated for "The Aviator" in 2004 in which he played Howard Hughes who was nominated for producing "The Front Page" in 1931.

Cate Blanchett won for the same movie in which she played 12-time nominee and 4-time Oscar winner Katharine Hepburn.

Nicholas Caige was nominated for playing screenwriter Charlie Kaufman in "Adaptation" in 2002. Kaufman, who had been nominated previously, won for the very same screenplay.

Gloria Swanson was nominated in 1950 for "Sunset Boulevard" in which she played fictional screen actress Norma Desmond. Her Oscar nominations were alluded to in the film and an Oscar can be seen on a table in at least one scene.

Kirk Douglas was nominated for "The Bad and the Beautiful" in 1952 in which he palayed fictional producer Jonathan Shields, whose Oscar nominations are talked about in the movie.

Robert Downey Jr. is the only actor I can think of nominated twice for playing someone nominated. He was nominated for "Chaplin" in 1992 for playing oft-nominated screen legend Charlie Chaplin and for "Tropic Thunder" in 2008 for playing fictional "five time Oscar winner" Kirk Lazarus.

Also I'm not sure about "A Star is Born". Both the leads were nominated in the original and the remake: Janet Gaynor, Frederic March, Judy Garland, and James Mason. Both characters were movie actors, but it's been so long since I've seen either movie. I kind of remember a scene at the Oscars...I need help on that one.

Are there any others?

Cate Blanchett is another double. She was nominated for playing Hepburn as you said. She was also nominated for playing Bob Dylan in "I'm Not There" and Dylan won the Oscar for best original song in 2000 for the song to "Wonder Boys".

You would think there would be more of these (Best Song), but I can't think of any more. A Lot of famous pop/rock stars have won or been nominated for Best Original Song: Springsteen, Prince, Lionel Ritchie, Stevie Wonder, Paul Simon, Eminem, Phil Collins, Elton John, Dylan - to name just a few. A lot of actors have gotten Oscar nominations for playing famous pop/rock stars: Sissy Spacek (Loretta Lynn), David Carradine (Woody Guthrie), Gary Busey (Buddy Holly), Angela Basset (Tina Turner), Laurence Fishburne (Ike Turner), Jamie Foxx (Ray Charles), Joaquin Phoenix (Johnny Cash), Reese Witherspoon (June Carter), Cate Blanchett (Bob Dylan). Yet, other than Blanchett/Dylan, they don't match up. (As far as I know).

not so sure David Carradine was nominated for that.

You're right, he certainly was not, I don't what I was thinking. (Bound For Glory got some noms including BP, but not Carradine).