I have over the years 5 certifications through NAUI, from 1975 to about 1982 (Jr Scuba Diver, Scuba Diver, Sport Diver, Advanced and Dive Master).
You should register them with NAUI so that NAUI can keep the records electronically should you need replacements in the future.
Don't take it personally, LOTS of records were burned in a fire truck when NAUI was moving its headquarters office from CA to FL.Thanks NAUI for remembering me