i have never seen a burnable two sided disc. the dual layers i have seen are two layers on ONE side of the disc. this makes it so you don't have to take the disc out and flip it half way through the burn. dual layer is slower to burn, compare the basic 2.4x dual layer and the basic 16x single dvd standards, although i have seen a dual layer burner that burns at 4x, it is a pioneer and i saw it in maximum pc magazine, but i don't know the model number.