I'm not sure either, as I also have not seen them before. But if they are Jabo Classics, I think it's really surprising that none of us have seen them before. I would certainly have taken notice, since they look so much like Vitros, at least to me. And I am sure that many of us have found groups of "same run" marbles in a larger group of marbles we found, perhaps marbles from the same bag or box that wound up in a mixed group, and I wonder if that's what we are seeing here.
And I do agree, it would be nice to see what Josh @Nantucketdink thinks of these.