The title is a biblical reference: on the sixth day, God made man. The movie is science fiction set in the near future where cloning animals is easy, and laws banning the cloning of human beings are called "6th day laws." Our hero is that epically untalented actor, Arnold Schwarzenegger. And what could be better than one Ahnold? Two Ahnolds! After a fairly regular day, Adam Gibson (Schwarzenegger) comes home to find that another him is already home ... Some unpleasant people try to kill him (Michael Rooker, Terry Crews in his acting debut, Sarah Wynter, and Rodney Rowland who looks almost exactly like Stephen Dorff). They all work for Michael Drucker (Tony Goldwyn) who can, in fact, clone human beings. Despite only being a helicopter pilot, Adam (notice that name?) is inevitably skilled enough to take on a crew of four assassins (several times - they get brought back after he kills them). The action is mildly entertaining. The movie made glancing passes at several morally interesting problems surrounding both the cloning of pets and the cloning of humans - and proceeded to not explore any of them (except for the evil profit motive of Drucker). It did however make it totally clear that cloning humans was bad. Unless the person cloned was someone nice like Adam Gibson. Then it was okay.
Had some charming moments, but it's mostly a vehicle for Schwarzenegger to ham it up (and he wasn't even doing it as well as usual). Fairly unimpressive.