The old cards are still valid.
Originally the records were kept on microfiche and your Hunter Ed number was your SSN. Licenses bought each year had a different number. With the REAL System we use now each person has a unique number assigned to them. The Hunter Ed card numbers issued now are not recorded, but new entries are assigned a number and it stays with the individual for life, same as a SSN. TWRA maintains historical Hunter Ed records and at your request it will be linked to your TWRA ID if it hasn't already. Hunters can even have out of state Hunter Ed added to their REAL account.
So if you took Hunter Ed years ago you can call a Regional Office and ask them to look it up and add it to your REAL account. Then if you need a duplicate card to show proof, one can be ordered thru the REAL System.