Who's to say they didn't? We aren't privy to every conversation they had once they discovered Khan's full name. How much imagination does it take to come up with an "unseen scene"?Okay, somebody explain to me how Spock, Kirk, et al never ONCE said - "oh, hey, they share the same name! What gives?" TBH, this was a stupid stunt. Let's face it -- one of many the MIC have committed. She could have easily had SOME OTHER NAME.
SCOTT: "Khan"? Wasn't that the name of La'An's ancestor?
SPOCK: Indeed. Lt. Noonien-Singh was often distressed by this.
KIRK: Run "Khan Noonien Singh" through the Library computer and see if there is a connection to our guest.
Or, what Mudd said.

