Alan,
> It was a party shot and there were dim, ghost-like strangers
visible behind the people who were posed for their photo.
The problem starts right here. What do ghosts (if they exist) look like?
Sort of the same thing as predicting what Martians look like. They might
look like ants ... or slime ... or?
We couldn't figure out how this happened. The camera wasn't capable of double
exposure. Very mysterious. Is there some quirky Polaroid thing that
allows this to happen?
At parties anything is possible!. ;)
But to be more serious I really don't know. Sometimes reflections in
doors, windows, etc. cause anomalous artifacts to show up. Careful review
of the conditions at the time the photogrpah was made is in order. I have
seen a pinhole in a Polaroid bellows throw a dim secondary image onto
the film plane.
