Double exposure is when you have two images layered on top of each other and you’ll change the blending options of the opacity of the images. Double exposure tends to create this dream like effect sometimes making the image look scary and give off a strange vibe but sometimes the photos can look very happy and sometimes nostalgic.

This style I believe comes from when Bernd and Hilla Becher who took photos of buildings then layered them together to create this creepy almost fantasy looking image.

I think the idea behind doing those kinds of photos is to create that kind of surreal effect for the image. Often photographers use double exposure to be able to add lots of deep and almost hidden meaning within their photos.