I understand the concept of double exposures, but I have not held a camera in my hands that can do it. All the analogue ones refuse to take a second picture and the digital ones, well, there is not even the option of not turning the film further.
Here are some images by Dan Mountford. He says they were created 'In camera" and that the colour was edited in photoshop.
Check out more of his images on the flickr link above or on fubiz.