You wrote
> It would be interesting to me if these names (
Jacob and
James, Latin Iacob et Iacobus) are really the same in Hebrew. <
As far as I can tell there is no Hebrew
James. Yaacov, and its variations, are
Jacob.
I searched briefly and came to this discussion; I'm sure there are others as well:
http://www.bibletexts.com/qa/qa138.htm