I don't know much about color variations, but have a look at the photo (my scan doesn't seem to be very good..hmm)
The first one is the correct color, but notice the color differences in the next 2.
Were these caused by the stamp being soaked off of the paper or were they printed this way?
The 2nd one, his clothes are much greener, and the 3rd one his coat is blue...
Any info would be great.