There's a reason why people hate their doppelgangers. They get to have sex with other people and you don't. If they want to, they can have sex with your partner. They're much better at gambling and snooker. That's why people want to kill their doppelgangers. Moore's favorite role.
Possibly Roger Moore's most atypical and best performance. The film has too little to offer besides Moore, it feels horribly dated (especially by the musical score) and stretched by its uninteresting subplots.