Great episode, very enjoyable. The best part of the episode, which has to do with the word "doppelgänger," concerns the local DC police team which the NCIS team works with on the case -- the DC team is practically a double of the NCIS team in makeup and mannerisms. It's a real scream, especially the reactions of Kate, who is dumbstruck by the similarities. I'll give just one of my favorite examples: the female member of the team tells the Lieutenant (the guy in charge) that his "ex-wife" called. He says, "Which one?" She says, "The nasty one." He replies, "You're going to have to be more specific!"
("Doppelgänger," by the way, originally had an ominous sense to it -- something like "a ghostly counterpart of a living person." Now-a-days it means any double or look-alike of a person, or a person who has the same name as another.)
Another winning aspect of the episode was Gibb's flirtation, dating and making out with a pretty computer-team supervisor. Lots of Tony-Kate bickering. Good Tim-Abby scenes for their fans.
The crime-detective aspects were fairly routine, but OK. NCIS started out with some false assumptions and suspects but eventually zeroed in on the culprit -- a nice surprise ending.
Thoroughly enjoyable episode, what with the mountain of quips, I was amazed it ended so soon -- the time just flew by so quickly watching it.