Here’s a video that clearly shows the advantage of having a dual-channel dashcam over a single-channel one.
YouTuber Vortex Radar uploaded a video in which he talks about not one, but three instances where the rear camera of his BlackVue DR750S-2CH dashcam was useful. In one case, the rear camera footage (which in the new flagship DR750S-2CH model records in full HD 1080p) helped identifying the culprit in a hit & run accident.
You can watch the video by clicking the thumbnail above or by clicking here.