Now in another genre, there's _Brat Farrar_, _The Ivy Tree_, _The Prisoner of Zenda_, and several others who flashed through my mind while I was hitting Reply, where the (sometimes only apparent) usurper or fake is good, and is applauded and re-accepted when revealed. Or worthwhile and/or gets reformed, as in _The Music Man_ or _Going Postal_.

Back to serious fantasy, in _Saint Camber_ the official hereditary king is a front for the real person/s in charge. Very cruel to the king; with all that illusion power, Camber should have done the impersonation himself and left the real king in his monastery.