Diego is far smarter than I am on these things. However, Barnabas is purportedly the same guy as Matthias from Acts 1 who won the Apostle Lottery. I only quote this Epistle to show how early the Sabbath switch started. I usually stop reading all things theological once they cross into the "false teaching" realm to try to keep from corrupting my data base.
When I was a heathen and was still into all that I never has anyone come to my door and try to evangelize me. As soon as I came to Christ I had more people knocking on my door and recommending books than you could shake a stick at.
By the grace of God He keep them people away from me and I was compelled to read the bible only for the first year or so of my walk.
Recognitions of Clement Barnabas and Matthias are one and the same according to Clement, Book I, Chapter LX about four fifths of the way down. [Disciples of John Refuted]
Sometimes I "smart" a little more than you....but smarter? I don't think so.
Realize, of course, that Clement is not scripture.