The stamps you show were definitives produced in huge quantities over a span of many years to be the workhorse stamps of their era. Just try to make a couple of billion of something over a span of 10 or 15 years and see if they all come out exactly the same.
I would not get caught up in small color/shade/hue differences - especially with used stamps which have additional handling and environmental aspects.
Also, in larger context, here is a typical machine cancel used in many German cities in this era:
