Yash Johar canceled shooting this movie in Prague due to the death of Juhi Chawla's mother. Due to heavy losses, Shah Rukh Khan cut down his salary.
Shah Rukh Khan told the media that the special effects in the film were the first in bollywood. The double role portions were not the old style of cutting the screen in half, then joining the film together in the editing table. In Duplicate the audience would see the double role's interacting with each other more closely. They would stand behind each other in shots, due to the advanced technology or film making.
Ek Shararat Hone Ko Hain was sampled from original Song - Laura Allen's 'Slip and Slide.
Kajol apperead in one scene
The song Ladna Jagadna was sampled from Ella Fitzgerald's 'A-tisket A-tasket and the Tom and Jerry theme music. Osibisa song Happy Children.