I haven't checked the actual web-site as I don't use Photoshop, but I love the effect and can see me using this myself. Where I pinned it from said "How to Create a "Double Exposure" in Photoshop — Daily Epiphanie"
Multiple Exposure Series by Simone Primo. I like these pictures because they cleverly join two pictures together. Because the pictures are in the shape of a person, the picture inside could be representing emotions/feelings.