I think ACI is a legitimate trope, and Amnesiac Liar is a poorly written duplicate. Well, ACI is poorly written, too; so I'm suggesting a rewrite below. AL can be split between cases where the person is intentionally trying to lose their memory (which leads to Memory Gambit) and cases where the memory loss was accidental, where because they were using some sort of cover identity, they don't have access to the right information (Amnesiac Costume Identity).
Such a character may have been victim of Easy Amnesia and now has to deal with the apparently faulty Amnesiac Resonance until they arrive at the Amnesiac Dissonance and decide for themselves which role they will keep.
Compare Memory Gambit; the character deliberately arranged for their memory to be lost and usually regained after their plot. Also Criminal Amnesiac; the "friend" deliberately lied to the Amnesiac to influence their behaviour.

Amnesiac Costume Identity seems to have been YKKTW'd without knowing that Amnesiac Liar already existed (and several examples overlap with it). There's a very strong overlap with Amnesiac Liar, perhaps we should merge the pages?
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