The stamps were issued to commemorate the 1936 Olympics in Berlin. There were also different cancels used at
14 different venues around Berlin.
It was common for collectors to post the entire Olympics set on paper or cover, then have the commemorative cancels applied as a collectible. Your cancels are from the Olympic Village. These stamps are very common legitimately used, and also very common as philatelic creations such as this. I wouldn't soak them off if I were you.