Those are really neat. I would assume most of them have to be studio creations, allowing careful staging of scenes and/or the use of masks to prevent unwanted "strays" from one exposure interfering with the other.

The one you called out, with the hand silhouette, I think I understand. Shoot the single hand first, against a bright background, with the exposure chosen so that the background just blows out while the hand stays quite dark. Then shoot the model as a normal exposure on the same frame. The portions of the model outside the hand won't show up: that section is already saturated from the first exposure. Inside the hand, the first exposure had little effect on the film, so all it "sees" is the model from the second exposure. Voila.

Same basic technique should work for the "head full of cigarettes" one. Some of the others completely mystify me, though! Take the second-to-last, with the bird flying in front of the model's face---what happened to the photons from that section of her face? Why isn't there something there overlaid on the darker bird?

-NT