You honestly think Walmart did that on purpose?
It was probably a bunch of "children" who's parent's let them run WILD in the store. Since there's usually no one around the pet department, one the little Einsteins probably thought it would brilliant & hilarious to put two of these FIGHTING fish together.
A few years ago I walked into a PETCO & found 2 m-bettas in a similar situation. These fish were fighting for probably several hours & had virtually no fins remaining. I brought the container over to a daydreaming employee so they were aware and asked them if I could have them, but they refused to SELL/give them away in that condition.
Back then I could have cared less about bettas. Anyway I had dinner plans with friends in the area, so I left. It would be interesting to see if I could have saved one of two, probably wouldn't have been able to do much though. At that period in time, I never had any experience treating fish with such badly damaged fins.
C'est la vie