In the treaty of modern schism Saint Vincent Ferrer explains If there were two popes at the same time, or the one would have more power than the other, or not. If one had no more power than the other, neither of them would be pope, because the pope has power over all, as has been said. If he had it, the inferior would not be pope.
Pope Innocent X specifically condemned the heresy of two popes.
Non veni pacem |The Splendor of Truth
I have written previously about Pope Benedict’s decision to retain the Fisherman’s Ring after his faux abdication HERE. At the end of every pontificate, without exception, the ring is smashed… with a special silver hammer that is made for this exact purpose and this purpose only. Several writers described the procedure in the days following the Declaratio. Then Benedict came out and corrected them. Oh no, dear friends, he’s keeping it. Huge red flag, along with retaining the form of address “His Holiness,” and all the other papal vesture, you know, because no other clothes were available.
The occasion itself is also very interesting. Did you know that antipope Bergoglio has always brought his newly minted cardinals in front of Pope Benedict for his blessing? After the first consistory, which Benedict attended in person, Benedict receives the new cardinals at his residence/monastery, where he imparts the his blessing. Could it be any more obvious that he’s not really retired?