It is possible to have a 3rd breast, now it being the same size as the others is kind of thin.
http://en.wikipedia.org/wiki/Accessory_breast
I did go to the site it was at and got the models name and googled it, she only has 2 breast so it is faked, but still a fantasy girl XD.
http://muffia.com/its-real/home.htm?id=noadvert
Model Name: Taylor Chanel (I believe, it was on the site)