Superclocked means it is factory overclocked for you which is slightly faster than the reference specs. It is tested to be stable before been packaged most of the time. This is EVGA terminology for factory overclocked.
Double dissipation is a fancy word for XFX to say hey we got dual fan coolers on our gpus.
ohhh ok so if i own the mother board : ASRock Z97 PRO4 ATX LGA1150 , am i still able to have two XFX (double dissipated) cards in there since it can hold dual crossfire gpus?