Understand, then, you children of gladness, that the good Lord has foreshown all things to us, that we might know to whom we ought for everything to render thanksgiving and praise. If therefore the Son of God, who is Lord [of all things], and who will judge the living and the dead, suffered, that His stroke might give us life, let us believe that the Son of God could not have suffered except for our sakes. Moreover, when fixed to the cross, He had given Him to drink vinegar and gall. Hearken how the priests of the people gave previous indications of this. His commandment having been written, the Lord enjoined, that whosoever did not keep the fast should be put to death, because He also Himself was to offer in sacrifice for our sins the vessel of the Spirit, in order that the type established in Isaac when he was offered upon the altar might be fully accomplished. What, then, says He in the prophet? And let them eat of the goat which is offered, with fasting, for all their sins. Attend carefully: And let all the priests alone eat the inwards, unwashed with vinegar. Wherefore? Because to me, who am to offer my flesh for the sins of my new people, you are to give gall with vinegar to drink: eat alone, while the people fast and mourn in sackcloth and ashes. [These things were done] that He might show that it was necessary for Him to suffer for them. How, then, ran the commandment? Give your attention. Take two goats of goodly aspect, and similar to each other, and offer them. And let the priest take one as a burnt-offering for sins. And what should they do with the other? Accursed, says He, is the one. Mark how the type of Jesus now comes out. And all of you spit upon it, and pierce it, and encircle its head with scarlet wool, and thus let it be driven into the wilderness. And when all this has been done, he who bears the goat brings it into the desert, and takes the wool off from it, and places that upon a shrub which is called Rachia, of which also we are accustomed to eat the fruits when we find them in the field. Of this kind of shrub alone the fruits are sweet. Why then, again, is this? Give good heed. [You see] one upon the altar, and the other accursed; and why [do you behold] the one that is accursed crowned? Because they shall see Him then in that day having a scarlet robe about his body down to his feet; and they shall say, Is not this He whom we once despised, and pierced, and mocked, and crucified? Truly this is He who then declared Himself to be the Son of God. For how like is He to Him! With a view to this, [He required] the goats to be of goodly aspect, and similar, that, when they see Him then coming, they may be amazed by the likeness of the goat. Behold, then, the type of Jesus who was to suffer. But why is it that they place the wool in the midst of thorns? It is a type of Jesus set before the view of the Church. [They place the wool among thorns], that any one who wishes to bear it away may find it necessary to suffer much, because the thorn is formidable, and thus obtain it only as the result of suffering. Thus also, says He, Those who wish to behold Me, and lay hold of My kingdom, must through tribulation and suffering obtain Me.
The Epistle unambiguously declares that the crucifixion of Christ is predicated on the binding of Isaac, as Justin Martyr would likewise say years later. The Epistle also connects this with the Yom Kippur rite of Leviticus 16, in which one goat would be sacrificed upon the alter and the another would be led away into the wilderness, baring the sins of the tribe. However, the Epistle equates both goats with the Christ, meaning that the Christ plays a dualistic role, one as a blood sacrifice and one as the barer of the tribe's sin.
Instead of getting hung up on a trivial detail that both goats are required to be of the same nature, we have an explanation why Barabbas was portrayed to be a murdering insurrectionist.
And when he has made an end of atoning for the Holy Place and the tent of meeting and the altar, he shall present the live goat. And Aaron shall lay both his hands on the head of the live goat, and confess over it all the iniquities of the people of Israel, and all their transgressions, all their sins. And he shall put them on the head of the goat and send it away into the wilderness by the hand of a man who is in readiness.
To take upon the sins of the tribe, Barabbas must be the sin. The Jews demand the death blood of Christ, an act of murder. Thus Barabbas must be a murderer. The Jews rebel, thus Barabbas must be a rebel.
Pilate plays the role of Aaron when he washes his hands of Christ's blood. It immediately recalls the act of Aaron placing hands upon the scapegoat and confessing onto it to transfer sin onto it.
And while the Barabbas episode is built around the Yom Kippur rite, it also reveals the mechanisms at work behind the earliest idea of the Christ Sprirt's transmigration. Just as Simon of Cyrene, coming in from the wilderness/country, is crucified in Jesus's stead, Barabbas is Christ liberated before death. It's why, after the episode, Barabbas disappears and is never mentioned again, again, just as Simon of Cyrene. Both Barabbas and Simon satisfy the meaning hidden in the narrative: Jesus may die, but he will return.
That is my interpretation. If you differ in opinion then that is okay. You are no less intelligent for disagreeing.