"It is called AMD Dual Graphics or asymmetric CrossFire and uses AFR (Alternate Frame Rendering) to render different frames on the two graphic cores. Therefore the combination also suffers from micro stuttering (different spaces between two images lead to stuttering altough the framerate is high enough for fluent gaming with only one GPU).
The performance of the Dual Graphics solution depends greatly on the driver support for the used games. In some games the performance may even degrade slightly compared to using only the dedicated graphics card. "