I think #1 points to the original usage. I believe it likely has its roots in sales commission accounting as these articles suggest. In that sense, it is probably a legitimate, domain-specialized usage. It seems to mean “after running the nominally new business through the rules that define new business for purposes of commission, what remains" (i.e., the "net"). In other words, “truly” new business, net of incremental extensions to existing business.
#2 explains how I am hearing it used. As is often the case with specialized qualifiers that roll off the tongue nicely (like "net new"--short, punchy, alliterative), all-too-quickly the specialized use morphs into a unthinking, generalized intensifier (see "literally" for the canonical example).