[2560] Repeat After Me

A horror-y short story for Halloween that I'd like to get some outside perspective and advice on. I especially want to know what you think of the ending.

Story: [2560] Repeat After Me

Critique: [3651] Something Noteworthy

EDIT with an additional question that's taken form: One thing (I hope) distinguishes the story from others like it is >!the reader can actually tell which Devesh is the real one. When the mimic copies Devesh but before they start talking at the same time, they both use words that have already been spoken in dialogue, except for one word which differentiates the real Devesh.!< Is this worthwhile enough to make the story stand out, and if so, how can I emphasize it without making it blandly overt?