2x 600w HPS/MH Circuit Breaker Question

Can 2 600w lighting systems including fans be run on a 15 amp circuit breaker if it is a dedicated room and nothing else is run on that breaker?

if the ballast are digital i think you might get away with it, hook it all up and try it out first...

sparky here - 600watt @120v = 5amps each
so yes, 2-600w on 1 circuit are ok, feel outlets/cords/plugs occasionally for heat - too hot to touch is too much - spread it out.
Rule of thumb - no more than 80% load for resistance loads (15 x .8 = 12amps max design load) ((resistance loads are anything with a ballast in it... etc))
You didn't mention fan watts/amps - remember to figure in those as well.