There are two kinds of dual channel , one is that the two camera are in the same body,which can shot the front and the rear. Another is the separate dual-lens, a main camera and a secondary camera that is like a car reversing camera, connected to the dash cam with usb cable.
In theory, the dual-channel dash cam takes a wider and more comprehensive. For example, some drivers in order to be in a hurry always like to merge over in traffic jams, so the accident happen simply and the auxiliary cameras can shot the video. Because of the advantage of the dual lens , one of them can be used as a reverse image or as a security inside the car, and we can switch the front and rear camera as we like .
But many of the dual lens dash cam are actually a gift that have more noise and is not clear to make much sense. But some regular bands of dual channel dash cam is relatively good, so more alluring.