Interestingly enough, Don Ingalls' first story outline of "A Private Little War" featured Kor, too. Bob Justman criticized this in a memo to Gene Coon dated May 26, 1967, and it was dropped.
What Bob Justman had to say on the subject is something fan films should take to heart. There's a tendency in fan films toward "small universe" mentality. Particularly, STAR TREK: PHASE II. It's stretching credulity by having Kirk continuously running into the same Klingon commander, Karagh, in their episodes.
I would suspect that
Star Trek Phase II is indeed the chief offender in this regard. In order to "continuously" run into the same characters, it presupposes that we are "continuously" generating episodes. I can't think of many other productions that generate enough episodes that there would even be any opportunity for such credulity-straining coincidences.
Obviously, of course, tapping into and relying upon the same people repeatedly (e.g. John Carrigan as "Kargh") is a cost-saving and time-saving measure--an important consideration for a production on a shoestring budget. But I think we do indeed suffer from "small universe" mentality. I think that's probably true of
Star Trek in general.