An interesting fact is at watches from the reference 6152/1, that there is no relationship between Rolex case number (engraved between the lugs) and the M.M. matriculation numbers, which are engraved on the caseback. Today we believe that the numbered watch cases (or entire watches) have been mixed after they were delivered (if they ever came in a matching number row out of Rolex) to their customer.

Good examples of this non-present relationship are 6152/1 watches 124527 (caseback engraved M.M. 023) and 124766 (caseback engraved M.M. 025). As the gap between 023 and 025 is only 1, the cases are 239 numbers away from each other.

Watch 124822 comes with engraved M.M. 066 caseback. Its 41 numbers higher than M.M.025, while their cases are 56 numbers away from each other.

The reason might be simple: caseback engravings (to use as a military matriculation number) may have been done by the customer and not by Panerai. What we find today let us think so. Additional, you can find no relationship on further details: dial versions, movement versions (Angelus 240 or Rolex 618), with or without crown protectors…