that's not what a pope is supposed to do. >> for 2,000 years the legacy of st. peter has been a define office passed on from one pope to the next. but can two men hold the legitimate claim to one godly office? >> it's left us with this situation of a pope and an extra pope. and that's always going to change the nature of an institution. >> who's the real pope? >> in 2013 millions of people watch as benedict xvi peacefully hands the papacy over to pope francis. but in the past, two living men with claim to one legacy has resulted in nothing but chaos. >> in the 10th and 11th centuries, if you've got two popes, you've got two factions. >> it's an extraordinary episode. >> benedict ix was a teenager,