Aren't the show tunes "Be a Clown" and "Make 'Em Laugh" suspiciously similar?
The finale of The Pirate (1947), with a score by Cole Porter, is a number performed by Gene Kelly and Judy Garland called "Be a Clown." In Singin' in the Rain (1952) Donald O'Connor does a famous routine to a song called "Make 'Em Laugh," whose music is identical to that of the earlier song and its lyric nearly so. Its authors, however, are listed as Nacio Herb Brown and Arthur Freed, who wrote the rest of the movie's score. How come? Were there any lawsuits? Both movies were produced by Arthur Freed, which may mean something.
Arthur Freed, the producer responsible for most of the MGM musicals of the 40s and 50s, began his career as a songwriter. "Singin' in the Rain" was part of Brown and Freed's score for MGM's first "all talking, all singing, all dancing" musical, The Hollywood Revue of 1929 (the song has since been used in five other films, counting A Clockwork Orange).
In 1952, Freed decided to use his songbook as the basis for an original musical, as he had done with Jerome Kern's songs in 1946 (Till the Clouds Roll By) and George Gershwin's in 1951 (An American in Paris). Freed assigned Betty Comden and Adolph Green to build a screenplay around the available material, with Stanley Donen and Gene Kelly to direct. When the time came to shoot, Donen decided that Donald O'Connor needed a solo number, and couldn't find anything that worked in the Freed catalog. Donen suggested that Brown and Freed write a new song, pointing to Porter's "Be a Clown" as the sort of thing he thought would fit in at that point in the script. Brown and Freed obliged--maybe too well--with "Make 'Em Laugh." Donen called it "100 percent plagiarism," but Freed was the boss and the song went into the film. Cole Porter never sued, although he obviously had grounds enough. Apparently he was still grateful to Freed for giving him the assignment for The Pirate at a time when Porter's career was suffering from two consecutive Broadway flops (Mexican Hayride and Around the World in Eighty Days).