At what point do Kirk, Spock, McCoy, and Scotty realize Kirk has been duplicated?
It seems like Shatner and Nimoy do a decent job conveying it after they hear McCoy said he saw Kirk acting crazy, and in the next scene Scotty shows them the mean dog and says, "if this should happen to a man..." Kirk says, "Oh my!" as if he rightly suspects it may have happened to him.
In the next scene Spock tells Kirk about Janice Rand having accusing him of attacking her. Given the last scene, you'd think they would telegraph that they suspect it may be related to the transporter malfunction. But they act like this is out of the blue. Are they in denial?
When they get more evidence, Spock says there's only one logical answer: we have an impostor aboard. Kirk acts surprised by the notion. Is this just Spock trying to protect Kirk's image and not be offensive? Are Kirk and Spock thinking but avoiding saying, "Crap, maybe you were split like that dog, and neither one of you is really the real person."
In the next scene Spock calls him Kirk's "double", which is appropriate. From this point on Kirk and Spock admit what has happened but hide it from the crew.
Do you think the writers/actors were trying to convey that they were talking around a sensitive issue, unable to speak of it openly? Or was it simply clumsy in drawing out the characters working out what happened?

It seems like Shatner and Nimoy do a decent job conveying it after they hear McCoy said he saw Kirk acting crazy, and in the next scene Scotty shows them the mean dog and says, "if this should happen to a man..." Kirk says, "Oh my!" as if he rightly suspects it may have happened to him.
In the next scene Spock tells Kirk about Janice Rand having accusing him of attacking her. Given the last scene, you'd think they would telegraph that they suspect it may be related to the transporter malfunction. But they act like this is out of the blue. Are they in denial?
When they get more evidence, Spock says there's only one logical answer: we have an impostor aboard. Kirk acts surprised by the notion. Is this just Spock trying to protect Kirk's image and not be offensive? Are Kirk and Spock thinking but avoiding saying, "Crap, maybe you were split like that dog, and neither one of you is really the real person."
In the next scene Spock calls him Kirk's "double", which is appropriate. From this point on Kirk and Spock admit what has happened but hide it from the crew.
Do you think the writers/actors were trying to convey that they were talking around a sensitive issue, unable to speak of it openly? Or was it simply clumsy in drawing out the characters working out what happened?