Actor Dominic Cooper studied Moon and Dead Ringers for tips on how to play two roles in The Devil's Double.
The Brit plays both Saddam Hussein's evil son Uday and his body double in the drama, and reveals he watched Jeremy Irons and Sam Rockwell portray multiple characters in a single film before his shoot.
And Cooper admits he "relished" playing dual leads - because it meant he was a permanent fixture on set.
He tells Britain's Esquire magazine, "I knew it would be hard (to play two characters), but I loved feeling part of it all. You can feel a bit removed on a film set, coming in to do your scene for one day, three days. You're a warm prop, really, which is why I relished doing this so much.
"I watched Dead Ringers, and Moon, which I thought was an incredible film, and I also looked at the brothers in The Social Network. But all those guys are meant to be twins or clones, whereas this is two very different people."