To put a more positive spin on this, the Kirk vs Kirk fight in Whom Gods Destroy is outstanding because of how well Shatner and the stunt double match. They actually put the stunt man in a Kirk Wig (or styled his hair, whatever) and when you do see the other man's face briefly, it doesn't shatter the illusion. The match is about as perfect as we were ever going to get. It sure looked better than the Star Trek III Kirk double who jumped off the cliff onto Kruge. That guy was 40 pounds lighter and 20 years younger.