

Construction worker Doug Kinney finds that the pressures of his working life, combined with his duties to his wife Laura and daughter Jennifer leaves him with little time for himself. However, he is approached by geneticist Dr. Owen Leeds, who offers Doug a rather unusual solution to his problems: cloning.
Acting
Keaton playing four versions of same guy, somehow distinct
Practical Effects
Pre-CGI split-screen effects actually hold up

Director
Harold Ramis
Trivia, insights & behind the scenes
Keaton improvised most of Doug #2's hyperactive nervous energy, making that clone the fan favorite.
This flopped hard ($21M vs $45M budget) and helped kill the 'high-concept comedy' era until 'The Hangover' revived it.