This one was intriguing: the double-exposure is the same scene taken twice, with the camera rotated 90 degrees to form the lines crossing each other. The bird hopped into the second photo just as I snapped it – it wasn’t my intent to include a bird in the frame originally. However, the light and the shadows on the right make this look to me like we’re looking through a window, with the glass not quite clear because of the sunlight. The bird adds to that illusion, since it’s different on either side of the panes of “glass”, left to right. Like the first photo, I don’t think you necessary see this at first glance as a double-exposure.

BTW, there is no “glass” in reality. It was a wooden fence along a path in the park.