Based on the Andre Gallant book titled - Dreamscapes, Exploring Photo Montages

Each of these images is a sandwich of two images. Those labeled Composite are made up of two different overlayed images. Those labeled Mirror are made up of the same image - one of which has been flipped (mirrored) before overlaying with the other. https://pbase.com/image/40622376 & its description give a good example of the Mirror Montage. The Surreals are two shots of the same image - one overexposed and in sharp focus, the 2nd exposed one-stop less and thrown out of focus - overlayed. The Cross is sort of a hybrid of Composite & Mirror. Two images are overlayed - one horizontal and one vertical & the final image is the square intersection of the two.