 Bhardwaj instructed the film 's entire cast and crew to watch caper classics such as Lock , Stock and Two Smoking Barrels ( 1998 ) , Snatch ( 2000 ) , Pulp Fiction ( 1994 ) and True Romance ( 1993 ) to study the nuances and become familiar with the genre . Shahid Kapoor played both Charlie and Guddu , twin brothers with speech impediments ; Charlie has a lisp and Guddu stammers . The producers did not want them to look like caricatures , so Kapoor prepared for both roles by meeting and interacting with speech therapists and people with these impediments . According to Kapoor , the producers wanted to find out about the medical reasons for the impediments and their mental effects . They met specialists and thoroughly researched stammering and lisping . Kapoor said that each role had its own challenges . Charlie 's physique was very different from Kapoor 's and it took him nearly a year to change the look of his body . He found changing from one character to the other difficult . 
