Star Trek: TOS 1.09: "What Are Little Girls Made Of?"

I wish I had Kirk around every time I have computer trouble. No one will ever be as good at talking computers to death than he was.

So, after this incident and and "The Enemy Within" issue, you'd think the crew of the Enterprise would devise some method of determining whether the captain was the captain or yet another evil twin. A pass phrase, a bio-scan, a tattoo on the real Kirk's thigh... something that's easy to check every time you run into the man to make sure he isn't evil. This would at least save some time when the Mirror Universe stuff goes down.

yr: 2266
sd: 2712.4
ad: 20 Oct 1966