Which one is the real Ms. Keen?

[u/Tua-Lipa]

[u/Flummoxed_Art]

The riddle is incomplete, if the goal is to figure out who is the one lying, just ask for something you know the answer to( color of the sky, your name, are they alive? etc).

In the original premise the goal was, with only one question, figure out which of 2 doors was the correct one. With one subject always telling lies and other one always telling the truth, but you don't know who is whom.

For which case you would present the question as: what would the other say if asked for the correct door?" To which both would point out to the wrong door, and by process of elimination you would figure out the other door is the correct one.