With the advent of portfolio photography and Photoshop editing and blending features, it has now become easy to compare the photos of two different people by stitching two halves of two
different faces and making one single photograph. Ulric Collete, a Canada based graphics designer and photographer, claimed to have accidentally found out this way to compare two photos of
different people. This was while he was learning Photoshop features and editing processes while he was taking lessons in photography. The photos in the link given above, shows us the differences
between two compared faces. Some photos even compare twins!