I do. Ask my parents, they went to a retirement celebration at the CIA for a friend they thought was a pencil pusher. Wrong! The whole time they knew him, he was deep undercover. The stories told at the celebration (nothing classified, of course) leave no doubt he did not use his real name at "work".
Aha! WHICH name is the "real" name?
When a friend of mine died, his wife was hysterical that she didn't have anything in his "CIA name". I calmly pointed out that he had published books in his "other" name, after he had retired. Noooo, that was a pseudonymn, not his "deep cover" name. Come to find out he had 3 names!
Oh well. You just never know who is who!