The biggest problem there is that the whole thing doesn't make a lick of sense. It would be like having a town in modern day America having a church arrest somebody for blasphemy and overseen by the state Governor who offers a choice between allowing a death row inmate go and punishing this person for blasphemy and having them let the inmate go. And then proceed to execute the person for blasphemy.
Really, it's exactly like the events the Bible depicts. There were actual Roman laws and they sure the hell didn't allow for insurrecters to go free or to arrest people for crimes that weren't real Roman crimes or to try them with secret Jewish cabals.
The only coherent analogy one could find is with the practice of scapegoating. Whereby a choice is made between two seemingly equal goats or in this case (sons of the father / Barabbas means "son of the father") and one is set free and the other is sacrificed, though rather than to carry away the sins of the Jews it is to condemn them and show guilt and culpability. It certainly doesn't make a lick of sense as a matter of history. (This might not even be an analogy but rather a homology if Dr. Carrier is right).