I have no idea what you are talking about

The fake information reminds me of the last time I went to the grocery store. The cashier said to the woman in front of me something like “Thank you Mrs. Smith” so I assumed she was a regular and the cashier knew her. When I checked out I fished out my rewards card and the cashier scanned it and said “Thank you Mr. Richards, have a nice day.” I almost said “Thanks but who is Richards?” But then I remembered I am Richards, that is the fake name I filled out years ago but no one has ever used it (and are they supposed to?)