The Great Gambler (1979)

Hired by a shadowy crime boss, a compulsive gambler unknowingly becomes the bait in a scheme to ensnare a patriot and steal classified military intelligence. When the police get wind of the plot, they deploy a strikingly similar undercover agent to intercept him. The problem? The imposter can't gamble to save his life, and every shaky hand and nervous bluff threatens to blow his cover and doom the entire operation.