The 'others' are clearly 'other Marcionites,' other than the 'official' claim that they only used Luke which is confirmed by the Acts of Archelaus where the bishop of Harran, Archelaus (the man who serves 'Marcion' viz Marcellus) repeatedly declares:
for our Lord Jesus Christ says of this Paraclete, He shall receive of mine. Him therefore He selected as an acceptable vessel; and He sent this Paul to us [AA 34]
the Paraclete, could not come into any other, but could only come upon ... the sainted Paul. For he is a chosen vessel, He says, unto me, to bear my name before kings and the Gentiles. The apostle himself, too, states the same thing in his first epistle, where he says: According to the grace that is given to me of God, that I should be the minister of Jesus Christ to the Gentiles, ministering the Gospel of God. I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost. And again: For I will not dare to speak of any of those things which Christ has not wrought by me by word and deed. I am the last of all the apostles, that am not meet to be called an apostle. But by the grace of God I am what I am. And it, is his wish to have to deal with those who sought the proof of that Christ who spoke in him, for this reason, that the Paraclete was in him: and as having obtained His gift of grace, and as being enriched with magnificent, honour, he says: For this thing I besought the Lord thrice, that it might depart from me. And He said unto me, My grace is sufficient for you; for strength is made perfect in weakness. Again, that it was the Paraclete Himself who was in Paul, is indicated by our Lord Jesus Christ in the Gospel, when He says: If you love me, keep my commandments. And I will pray my Father, and He shall give you another Comforter. In these words He points to the Paraclete Himself, for He speaks of another Comforter. And hence we have given credit to Paul, and have hearkened to him when he says, Or do you seek a proof of Christ speaking in me? and when he expresses himself in similar terms, of which we have already spoken above. [AA 35]
So then Christ, our most patient Lord, has through all these years borne with a perversion of the preaching about himself, until, if you please, Marcion should come to his rescue. [Tertullian Adv Marc 1.20] As corrector apparently of a gospel which from the times of Tiberius to those of Antoninus had suffered subversion, Marcion comes to light, first and alone, after Christ had waited for him all that time, repenting of having been in a hurry to send forth apostles without Marcion to protect them. [Adv Marc 4.4] "the type of the Paraclete, Paul became the Apostle of the Resurrection" (ho Paulos anastaseōs Apostolos gegonen) [Theodotos 23]
Mani clearly grew out of the Marcionite interpretation (for he claims he is the Paraclete in the text. So too Muhammad for they all used the same 'Diatessaronic' gospel text which identified the Paraclete as a person rather than the Holy Spirit. One must also suspect that pre-canonical Montanists similarly used a Diatessaronic gospel with this understanding.
"Certain followers of Marcion identified the 'other Paraclete' of Jo. 14,16 with St. Paul; cf. H.B. Swete, The Holy Spirit in the Ancient Church (London, 1912), 65-66 Certain followers of Marcion identified the 'other Paraclete' of Jo. 14,16 with St. Paul; cf. H.B. Swete, The Holy Spirit in the Ancient Church (London, 1912), 65-66 In his Homilies on Luke 25,5, after discussing the Marcionite exaltation of Paul, Origen says that "Others read the passage, 'I shall send you an advocate, the Spirit of Truth' [Jn 14,16-17] and... they take it to mean the apostle Paul" (trans. J. Lienhard, Origen) [Rosenstiel the Apocalypse of Paul p. 151]