Me, Myself and Irene (2000)

Meet Charlie Baileygates, a 17-year veteran of the Rhode Island police force. Charlie is mild-mannered, hard working always helpful, and a devoted and loving father to three sons. Unfortunately, Charlie has Split Personality Disorder, and when he runs out of his medication... Meet Hank Baileygates, Charlie's hyper-aggressive alter-ego. Hank's got a filthy mouth, drinks like a fish, breaks skulls and loves dirty, dirty sex. Charlie and Hank have nothing in common, with the exception of Irene Waters, a beautiful woman on the lam with whom they have both fallen in love. Now, Hank/Charlie must wage war - with himself - for the confused Irene's affections.