[s3e20]: Imposter

Palmer leaves the real Harm bound to a chair in his apartment, which he has booby-trapped with a motion sensor bomb. The bomb is set to detonate if Harm moves or after eight hours.

Details on other throughout the series.

Played both the real Harm and the imposter (Palmer in disguise). Clark Palmer [S3E20] Imposter

Palmer captures Harmon "Harm" Rabb Jr. at his apartment on the morning of the trial. He incapacitates Harm and uses a sophisticated process to create a life-like mask of Harm’s face, effectively assuming his identity. Palmer leaves the real Harm bound to a

Alan J. Levi (though some sources credit Kenneth Johnson). [S3E20] Imposter

The episode is noted for its "Mission: Impossible" style face-masking technology, which was a popular trope in late 90s action media.