They made a mistake photographing it with a wideangle, makes the join far more obvious than in the colour one.
The illusion of 3d, made with old stereo cards, those old photographies from the 19th century that contained two different views of the same subject to give the illusion of depth. He converts them into pseudo-3D GIF images which can be seen without glasses, in your monitor. [Stolen from Giz]
btw - this site is an amazing resource for interesting photos: http://pixdaus.com
Hardly real quality but the expression on this dog's face as it decides too late to abandon jump is fucking funny