Someone keeps trying to open a credit card under my brother's name.

About a month ago I applied for a Walmart One Pay Cash Rewards credit card and was accepted. About 2 weeks later I get a letter in the mail addressed to my brother which was a denial letter for the same card. Only thing is that he is in prison and has been for the last couple of years. a couple of weeks after the first denial letter, I got another one addressed to him to my home. Is someone trying to steal his info? I just think it's crazy because I got the same card a month ago. How would someone have access to this information? What should my brother do since he's locked up? As for the letter coming to my house, he used to live here years ago. Does anyone have any advice?