To me, "double camber" means something else. Maybe I'm dating myself. To me it refers to a classic xc ski that has a "first" or "long" camber that collapses fairly easily, and then a "second" or "kick pocket" camber immediately underfoot that will only flatten when all your weight (plus extra down-force) is on one foot. The idea is that when you're in the glide phase the kick zone is off the snow, but you can still engage the kick wax (or fishscales, or whatever) briefly when needed.
Actually, I think they call it "triple camber." I don't know from xc skis, though, come to think of it, I did that before I did alpine, il y a longtemps.