Now I know why she signed this "Sunset Blvd"! Its one of the photos Norma is signing in response to letters that Max writes. See the photos on the table in the scene from the film:
Wow! That is super cool. I love that movie and IF she actually signed this particular photo in the film that is even better. Even just having the same type of photo in the movie and your photo having “Sunset Boulevard” written on it is just so awesome.
Thank you. I seriously doubt she signed that during the film - it's just very unusual to have one of those prints with the 1949 date. And I love this film.