Yes, it has happened before.
In 449, Emperor Theodosius I convened what was supposed to be an Ecumenical Council in Ephesus along with the bishop of Alexandria called the "Pope of Alexandria", the decrees of this council were heretical and it was condemned by Pope Leo I as a "council of robbers" and he convened the real Ecumenical Council of Ephesus in 451, which condemned the decrees of the previous council.
It was probably about this time that theologians first started arguing that the way you can tell the difference between an Ecumenical Council and a fake "Council of Robbers" was that the authentic councils are the ones convened by the bishop of Rome , or at least have their decrees approved by the Pope
|