Yes, they can! Check out this link. I've heard that most double yolkers have problems hatching if they even survive incubation.
Incubating and hatching double yolk eggs is not recommended. It is very rare that they get to the end of the incubation period and if they do they are not able to hatch themselves as there is not enough room in the egg for them to turn to be able to hatch. Also if they do get to that point one chick or both chicks are more than likely to be weak and unable to survive the hatch or very long after hatch. This is the reason why I would not incubate a double yolk I couldn't watch the chicks suffer after hatching and then die.
X 2 - most hatchers consider it irresponsible to intentionally set out to set/hatch a double yolked egg.
