there seems to be some confusion about double clutching and a dual clutch transmission.
double clutch is a driving technique, a way of shifting a manual transmission that involved depressing and releasing the clutch twice when shifting
Double clutch - Wikipedia, the free encyclopedia
Dual clutch is a type of manual transmission that utilizes two clutches to achieve very smooth shifts compared to regular automated manuals such as the BMW SMG(since replaced with a dual clutch design)
HowStuffWorks "How Dual-clutch Transmissions Work"
Twin-clutch gearbox - Wikipedia, the free encyclopedia