There are a few possibilities:A: You already have imported the PGP key... That implies the vendor is using the same public key for two different SR accounts, one of which you've already messaged before now.B: The vendor doesn't have their PGP name/email as something similar to their SR username. I have dozens of contacts who are almost worthless because of that practice, it's a pain in the ass to double check who is who if you don't use your SR username as something similar to your PGP handle/email. It doesn't improve your anonymity and it doesn't help anybody who wants to send you an encrypted message that's for sure.