it should be strong enough to cool two lights as long as they're air cooled, just hook them up together in a line and make sure you have a source for the fan to pull in new air through the room as its exhausting the hot air out of the room, through the hoods and then preferably outside. *hint ALWAYS make sure your pulling air across the bulb, meaning the round end of the bulb should be FACING the direction of the incoming air. It'll help fix the aerodynamics of a square reflector alittle.
If you do this and your CANOPY tempurature isn't below 82ish at the hottest point in the day you might want to consider moving the lights further away from the plants.
If the'yre not air cooled your gonna have helluva time trying dude I know people who went there and to no avail....
350cfm should be good for 2 lights, I know a guy using a 424cfm with 3 600s and his avg temp is around 78. KEEP IN MIND the best temp is 75 lights on 60 lights off, no less than 55. Rule of thumb is you want to try and get a 15 degree drop when the lights go out. Hope this helps.