It’s a mutual admiration society on the cover of World’s Finest 22 (May/June 1946).
William White is the artist on the Zatara story in this issue.
A criminal who slightly resembles Zatara notes how much deference the police give the magician. He decides to make himself look like the hero, and exploit the trust Zatara has.
It works very well at first. The police stand aside, waiting for Zatara to use his magic on some bank robbers, not realizing that the phony Zatara is in league with the thieves. The phony Zatara winds up causing the police to turn against the real one.
Of course, this only works until the fake gets confronted by the real Zatara. One genuine magic phrase, and the deception is revealed, Zatara’s name is cleared, and the bad guy is taken to prison.