In the show La femme Nikita, there is a classic doppelganger trope in S03E07(Cat and Mouse), where Nikita has been kidnapped by an organization who then plants a doppelganger in the section who she is supposed to guide in real-time to deceive them.
I can't figure out how exactly Nikita gave them her location so they can rescue her. I can understand how and why they might figure out the double isn't really her. The only reason I can think of it could be her tracking implant, but it's not mentioned at all. And probably they can block such scans since in S04E18 where she is held by a crazy guy in his basement, Madeline says such organizations can block IR and RF scans.
I really wish they would have given the answer at the end when the guy in charge ask her how she gave Section her location. Any ideas how it could've happened?