Ah, is that what a flam is? Swervedriver: I think it may have more to do with the fact that one is played by a human and one is not.
But regardless, it's hardly a bad thing-- I think it sounds amazing! "A Senile Animal" by The Melvins is another awesome example of the double drumming thingy, the drums are very natural and un-triggered on that album so it just sounds even more amazing and huge. I really wish it was used more often, it gives the sound so much more weight and substance, it's fantastic.
Actually, I think the drummer from Lamb of God doubles his tracks. I've heard very brief mention of it and if you listen carefully on some songs you can hear... erm... flams..? on the kick drum and such. But I digress
~Josiah