A 200% hatch rate would mean that you've hatched twice as many eggs as you had.
Somehow, unless you're implieing that if you let the mom incubate the eggs, every egg turns out twins somehow, I don't understand the numbers.
I've heard from several people maternally incubating without success. I know some people do it successfully, but I prefer to artificially incubate myself. I like to get mom eating as soon as possible, and I prefer controlling the temps and all a bit more precisely.