The article implies that there was no Photoshop work, but you can replicate the effect with the various blur filters (I experimented a bit and found motion blur, shape blur, and lens blur to be best for this) and adding some noise and color adjustment. Put each blur effect on a different layer and play around with opacity until you find the right balance for your picture.
Looks like a double exposure on Polaroid 665.
As you can see from the hand positions, there are two different shots on the same neg.
Sarah Moon and Paolo Roversi used to work with that type of film all the time.