Abstract: A system for detection of doubles in a stream of flat items such as mail pieces being conveyed on a conveyor includes an electronic imaging camera positioned to receive an image of a side face of conveyed items over a first portion of its field of view, a reflector positioned to reflect an edge view of the items to the imaging camera, which edge view is received by the imaging camera over a second portion of its field of view, and a computer that receives image data from the camera. Program logic used by the computer determines whether the image shows one item, or more than one item.