I’m surprised most makers didn’t just skip over that serial number just like most buildings don’t have a “13th floor” even when the number of floors exceeds 13....
Incidentally, the irrational fear of the number 666 is called hexakosioihexekontahexaphobia
Many biblical scholars are of the belief that the actual number of the beast is 616, not 666, fyi. So, you have another number to check for if you want to buy that argument. Just saying'.