Easy to get his confused. AMD "Dual Graphics" is relatively new, and combines the on-chip graphics of A6, A8, and A10 chips with a *LOW* end discrete graphics card. Officially up to a 6670, unofficially 7670. Only Directx10 and 11 are supported, and only Vista and newer OS. If a more powerful card is used the on-chip graphics are disabled. While Dual Graphics was a nice idea, it is rarely used since most people buy a decent video card which quickly outperforms any Dual Graphics combination.
Much more common is AMD Crossfire or Nvidia SLI, which uses two dicrete video cards that are virtually identical.