"This town ain't big enough for the two of us, see..."

Overused in westerns, but coined, I believe, by E.G. Robinson's Cesare Enrico Bandello roll in "Little Caesar" (1930)??

Director Mervyn LeRoy wanted Clark Gable to play Joe Massara in the flick. After the screen test, though, studio execs decided Gable could never become a star, because of his unusually large ears. Douglas Fairbanks got the piece.

As for the quote, it's been repeated countless times, and in many, many forms. Even pretty Doris Day, as Calamity Jane, gave it a "shot":
"This town ain't big enough! Not for me and that frilled-up, flirtin', man-rustlin' petticoat, it ain't!"

Dan