There was only one Pope. One was the arrogant western barbarian Pope, the fool who thought that he was given godly authorities and ruled over the world and wreaked havoc on the city of Rome for a thousand years. The other one was the true one, the Ecumenical Patriarch, in Constantinople.
The western Pope originated as the official Bishop of Rome under the Roman Emperor's absolute authority. Within a few years Western Roman Emperors started to use other cities as their bases (Ravenna and Mediolanum in particular), and the bishop unofficially gained power inside the city and started to shadow-control of some offices and positions in ruling the region. By 400 AD, Roman Empire was beginning to collapse. In 406, barbarians invaded in huge numbers and could not be stopped. In 410 they invaded Italy itself and sacked Rome itself, a huge shock of the era and reduced the city from the population of almost a million to a city that had barely 100,000 people. From then on, Western Roman Emperors were completely distracted with handling the painful collapse and disloyal generals, and the bishop of Rome increasingly got in control. By 450 AD, he was in unofficial command of the entire Latium province, and had ability to negotiate in diplomacy like a fully independent warlord.
Then by 476, Western Empire was almost completely gone except for a province in Dalmatia, a piece of land in northern Gaul, and Adriatic islands. The bishop was free to reign independently, which he did under (Christianized) barbarian protection. He was again put into his rightful position when Emperor Justinian reconquered entire Italy, and remained so until the time of Emperor Maurice and Heraclius. He was also kept separate from l Then the Roman Empire lost Italy again, and collapsed heavily after Arab invasion, barely retaining Anatolia and some lands around Constantinople.
The Pope was free again, and now that there was no powerful Roman Empire to keep him in check, he grew arrogant and began considering himself as master of Christianity (and all Christian states). Then he went on to crown a false menacing barbarian wannabe usurper as 'Roman Emperor' when that little arrogant
had no authority to do that. The real Roman Emperors were struggling to hold what remained of the empire.
Comparable to an insane situation like a little African country crowning one of their politicians "Presidents of the USA" (when real ones exist) and then decieving every man within their grasp that
he is the real one and the one actually ruling USA is a false one.
Then the western barbarian wannabe's continued to believe that they have reformed the Roman Empire and all it's glory, while continuing their barbaric ways and pillage and looting. Real Romans recovered some and returned into a partial Mediterranean superpower, but the barbarians continued to believe the arrogant Pope who pulled strings from behind using religious threats and warnings, and his false forged 'empire' that was ruled by barbarians.
And a lot of western barbarians pretending to be civilized (still doing that) continued to believe it to be the true Roman Empire until 1807, while real Roman Empire collapsed yet again, made another partial recovery and finally vanished, being massacred and sacked by even more gruesome and cruel Turkish barbarians from the east.
Or so it seems. This was partially true. But the Pope had grown too much out of his shoes, and become too arrogant and independent-minded to be controlled. The barbarian refused to recognize Ecumenical Patriarch as a superior in the compromise of being offered to be declared the official Patriarch of Rome, and then the barbarian bishop went out of his way to create a new false nation full of barbarians and give it the name of a glorious old empire now in peril, and decieve them to believe that the new one is the real one. The barbarians readily believed, and pretended to be civilized Romans just because they learnt how to speak Latin.