There are no official decrees against 'the Marcionites' anywhere in the literature. Yes the term certainly was used to describe a sect in the Patristic literature but the Marcionites themselves identified their tradition as 'Christian' or 'Christianity' (and the Catholics as 'refugees' at least in the lands outside of the Roman Empire). This very terminology of 'Palutians' of a certain 'Palut' bears striking similarities to what I suggest developed with respect to the 'Marcionites' of 'Marcion' (and the 'Ebionites' of 'Ebion' and the 'Elxasites' of 'Elxai'). In other words an unfamiliar Aramaic word is developed into the name of a sect leader where no real historical individual existed before.
The forms of names of sects can vary from author to author and from ms. to ms. Thus the Dositheans are called Dosithaioi, Dosthenoi, and so on. Those who will inquire into matters will see that the Samaritan chronicler Abu ‘l-Fateh. uses a sources that had Dosthenoi, since he calls the Dositheans Dostan or Dustan (a collective plural form in Arabic). The translations of the Greek sources hardly ever give this kind of information.
We can compare Epiphanius’s invention of a person called Ebion, founder of the group called Evyonim in Hebrew. (Though the form evyon is a unit and the form Marqiyon- is a compound). The suffix –iyon is productive in Hebrew and Aramaic of the time - productive is a technical term of theoretical linguistics meaning used to make new words, as opposed to being recognised in existing words but not used to make new words. It does not make diminutives: it makes derivatives. PEOPLE don’t have names ending in –iyon in Hebrew or Aramaic, but THINGS named by relation to other things have the suffix.
The logical assumption here is that the Greek Markion is a combination of influence of the Aramaic and a conscious creation of a Greek diminutive. The gentilic collective plural meaning 'those of Mark' is Marqiyônê (singular Marqiyona). The underlying material behind the third century invention of 'Marcion' were written in Aramaic (again based upon our assumption of a collision of Alexandrian and native Semitic Christians in Palestine in the late second century). The Aramaic sources originally identified 'those of Mark' and a 'Mark' (undoubtedly St. Mark originally) the corrupt Greek developments of these original texts developed these references into 'Marcionites' (= Marqiyônê) who had 'Marcion' as their leader.
It is easy enough to explain away the two additions to Justin's Apology but what about Irenaeus's classic reference to Polycarp rejecting 'Marcion.' A careful examination of the original material in Against Heresies shows how naturally one might have developed from the other where Polycarp is said to have been:
and a more stedfast witness of truth, than Valentinus, and Marcion, and the rest of the heretics. He [Polycarp] it was who, coming to Rome in the time of Anicetus caused many to turn away from the aforesaid heretics to the Church of God, proclaiming that he had received this one and sole truth from the apostles,--that, namely, which is handed down by the Church ... Polycarp himself replied to Marcion, who met him on one occasion, and said, "Dost thou know me?" "I do know thee, the first-born of Satan." [AH 3.3.4]
This reference is almost universally understood to reference the conversion of Marcionites and Valentinians at Rome. Yet Against Heresies deliberately avoids the difficulty of great Marcionites already at Rome before Polycarp's visit coupled with Polycarp's well known hostility to Anicetus.
Irenaeus's solution is to argue on the one hand that Polycarp and Anicetus only 'agreed to disagree' about the date of Easter. Of course few scholars now see this dispute to be so limited. Anicetus clearly agreed with Victor's anti-Quartodeciman stance and Polycarp was a Quartodecimanist. The fact that Victor supported the Alexandrian position on Easter opens the door to the idea of further and deeper agreements between he, Anicetus and the Marcionites. That Polycarp, rather than Anicetus, is doing the work of 'confounding' and 'condemning' these heretics is very telling. They may well have been one and the same with 'those of Mark' (= Alexandrians) already established in Rome from a much earlier period and perpetuated through an apostolic succession through Anicetus and Victor.
All the evidence seems to point to the fact that the great attempt to reconcile the two churches in Rome and indeed throughout the Roman Empire occurred under the reign of Zephyrinus (= early third century) and embodied in the Muratorian canon. The Muratorian canon interestingly makes only two references to 'Marcionites.' The first is an allusion to 'scificate sunt fertur etiam ad laudecenses alia ad alexandrinos pauli no mine fincte ad heresem marcionis' - i.e. a letter to the Alexandrians associated with the 'Marcionite heresy' and the second to 'novu psalmorum librum marcioni.'
The first reference is corrupt but is generally assumed to refer to two Pauline letters which were renamed in the Marcionite canon. I have assumed that just as Ephesians was renamed to the Laodiceans, the letter to the Corinthians was renamed 'to the Alexandrians' and that - given the Marcionite (see the ordering in several references in Tertullian's Against Marcion) and the Muratorian's Corinthians first canon, the Marcionite canon clearly reflected its Alexandrian origin (Cerdo the forerunner and Apelles the successor of Marcion are both connected with this See).
The point then is that everything seems to point to the existence of the presence of a group of followers of Mark already present in Rome before Polycarp's visit. My guess is that the shared position on Easter between Victor and the Alexandrian Church extended to Anicetus and that Polycarp's hostility to both Anicetus and the Marcionites is ultimately rooted in the traditional Asian hostility to the Alexandrian tradition.
None of this helps explain the claim that Polycarp actually met and confounded the historical Marcion at Rome other than the fact that Jerome is commonly regarded to have mistaken Marcellina the Carpocratian for Marcion (both Marcellina and Marcion being diminutives of the Latin name Marcus - one male the other female). A separate tradition emerged in the Hypomnemata of a heretic with the diminutive of the name Mark who I believe became confounded (deliberately or accidentally) with the head of the Marqiyônê (= those of Mark). In other words, the story of Marcellina becomes associated with the 'followers of Mark' already in Rome and the figure of 'Marcion' is ultimately born (itself appearing as a Greek diminutive of the Latin name Marcus).
This is why the emergence of the figure of 'Marcion' only appears very late in the literature. It depends on a gross misreading of an appendix added to the original work of Hegesippus dated to the beginning of the reign of Commodus's joint rule with his father Marcus Aurelius. The original text - cited almost verbatim in Epiphanius and Irenaeus looks back at the coming of Marcellina in the following terms:
From among these also arose Marcellina, who came to Rome under [the episcopate of] Anicetus, and, holding these doctrines, she led multitudes astray. [AH 1.25.6]
That a gross corruption occurred with material related to this text is found in the difference between Celsus's original citation of another section of text (i.e. the 'Harpocratians of Salome' which is transformed into a sect called 'the Carpocratians').
If Harpocratians can be corrupted into Carpocratians, the female heretic Marcellina could be transposed into a male heretic Marcion. Indeed Jerome's treatment of Marcellina as the original Marcionite in Rome testifies to such a corruption process. Interestingly again in the case of Marcellina she was indeed an Alexandria undoubtedly representing in some manner (or 'connected with') the Alexandrian tradition of St. Mark. Clement goes out of his way to deny the connection, nevertheless the Egyptian roots of the sect and its association with an early text of the Gospel of Mark shoot down these claims.
I would argue of course that just as the canon became fixed at the beginning of the third century in order to bring order to Christianity, it became equally necessary to explain the various and conflicting stories associated with the heresies. To this end, what was a 'Marcionite,' what was a 'Marcosian,' what was a 'Carpocratian' only became fixed at a later date. One could argue that different reports would name the same historical tradition by different names owing to the fact that the terminology was by its very nature hostile and unscientific.
That the 'Marcion' reference in Irenaeus's Against Heresies Book Three needed to have the identity of 'Marcion' explained while the term 'Marcionite' was well known implies again to me at least that the name 'Marcion' came subsequent to the widespread use of the term 'Marcionite':
This account Gaius copied from the papers of Irenaeus. The same lived with Irenaeus who had been a disciple of the holy Polycarp. For this Irenaeus, being in Rome at the time of the martyrdom of the bishop Polycarp, instructed many; and many most excellent and orthodox treatises by him are in circulation. In these he makes mention of Polycarp, saying that he was taught by him. And he ably refuted every heresy, and handed down the catholic rule of the Church just as he had received it from the saint. He mentions this fact also, that when Marcion, after whom the Marcionites are called, met the holy Polycarp on one occasion, and said 'Recognize us, Polycarp,' he said in reply to Marcion, 'Yes indeed, I recognize the firstborn of Satan.' The following statement also is made in the writings of Irenaeus, that on the very day and hour when Polycarp was martyred in Smyrna Irenaeus being in the city of the Romans heard a voice as of a trumpet saying, ' Polycarp is martyred.' [Martyrdom of Polycarp Moscow MS]