Hello Bill, if their assumptions are accurate, after carefully analyzing the clock of Philipp and the mine I can confirm without any doubt that the clock of Philipp and the mine are "brothers" (can check by studying two watches) This gives to suppose that it is not a printing error, as some say, but in my opinion, prototypes or pre-series production of the network , the two have the 2.1xx xxx serial number.
Thank you your interest by my watch, I am very proud to own it.
I am at your disposal for any clarification or provide more data