Mark in Paris[Purist]
10488
mouvement number
First, welocme on our forum Anthony and huge congratulatiosn for your Perpetual Calendar.
About your number issue, it seems that there has been different versions of the calibers (and not only 324) as time goes by. Furthermore, I'm not sure the calibers pictures shown on the website are always updated with the latest one. I don't know how it is updated really but noticed sometimes a few differences in the past.
Thus, I wouldn't conclude on this.
I suggest you contact any Patek authorized retailer or Salon, with your numbers (they may ask you to come with the watch), and they will tell you.
It is quite less likely that a 5396 was copied in a faithful way (but without pictures it is impossible to tell).
Enjoy it !
Best, Mark