I'm not sure exactly who said you don't double dose. I'm not positive, but I don't think AP willyour Glut-4 receptors, but perhaps it is an issue of diminishing returns.
To me is like a very strong AP ( I know diff. in compounds), but since can further enhance glucose uptake, I think there should be atleast some benefit from 2 AP's vs. 1 . Mullet will find his way here