I didn't think about it when I lived in San Diego, eating Mexican combo platters as routinely as we eat pizza in the East. I didn't think about it back when I was copyediting the food section of the Boston Globe. Decades have passed, and now, at last, Trader Joe's has answered the question I was always too dim to ask: Why do we call them "refried beans"? Are they really fried twice?
Apparently not. According to the Fearless Flyer that arrived in today's mail, the name results from a mistranslation: "In colloquial Mexican Spanish, the prefix re is often used to mean 'very.' So frijoles refritos should actually translate to very fried beans, not refried beans." A number of other websites say the same, and Snopes.com concurs, citing Diana Kennedy's "Cuisines of Mexico." (Kennedy's a reliable source, or at least she was in my food editing days.) So until I hear otherwise, I'm accepting that refried beans are fried only once.
I also wondered (at long last) why the beans needed to be fried even once, since they can be simmered and mashed into the desired state of submission without the skillet treatment. But now that I've looked up a few recipes, I think I understand.