The Marina Militare is the Italian Navy.
It is my understanding that most if not all of the 202/A's were issued to Marina Militare officers and only become available when a officer or his family decide to sell it.
All of the other MM watches are produced with the approval/permission of the Marina Militare. So they all are special editions and are done infrequently.
I hope this helps. Please, if any of the Panerai experts has anything to add, please do.
Bill