Me, Myself & Irene (2000)

Charlie is a Rhode Island state trooper with a split personality. He is otherwise mild-mannered and non confrontational until somebody or something pushes him a little too far. That's when his maniacal alter-ego, Hank, takes over. Charlie is assigned on a routine mission to return alleged fugitive Irene back to upstate New York, but they wind up on the run from corrupt police officers. And their escape would be a lot simpler on everybody involved if Hank didn't keep stepping in at the most inopportune times... (imdb)
Cast and Information
Directed By: Peter Farrelly, Bobby Farrelly
Written By: Peter Farrelly, Bobby Farrelly, Mike Cerrone
Starring: Robert Forster, Richard Jenkins, Lin Shaye, Jim Carrey, Chris Cooper, Renée Zellweger, Natassia Malthe, Tony Cox, Traylor Howard, Libby Langdon, Jerod Mixon, Michael Bowman
Genre: Comedy
AKA: Me, Myself and Irene
Country: USA