BEFORE you order a duplicate card, please look at your Texas Hunting License for "HE#XXXXXX" (with numerals replacing the X's). This is your certification number. If your license includes your certification number, you do not need to order an additional Hunter Education Certificate to hunt in Texas. If you intend to hunt outside of Texas, you may still need to have a duplicate card.
If you took the course in another state, you will need to contact that state agency for a duplicate copy. Texas recognizes all other states' Hunter Education Certification, but you must carry proof of certification on your person while you hunt in Texas.