DIscover has nothing to do with the Walmart Discover. The Walmart Discover is issued by GE. They are the ones lending you the money, not Discover. GE and Discover have different criteria. You qualified for the Discover IT with their criteria and for the Walmart card with GE's criteria. Use the card and PIF for the best chances of getting upgraded down the road.
You can think of it like a Chase Freedom card has nothing to do with Visa. Chase backs the card and lends the money, it just runs on the Visa network.
Same situation for me, but I am actually ok since I rarely use the Walmart card.
P.S. - Your sig shows you have the Walmart Discover so all is good
“Beware of little expenses. A small leak will sink a great ship” – Benjamin Franklin
Gardening since 3-26-15