Kanigher, Hasen and Belfi bring the Harlequin back in All-American 94 (Feb. 48). The story picks up right where the previous issue left off, as Alan Scott discovers that the Harlequin has escaped from prison.
When Molly tries to draw attention to her new bracelet, Green Lantern gets the inspiration to lure the Harlequin out with a beauty pageant, figuring her ego demand that she enter.
Although it is not shown this way, one has to assume that the Harlequin uses her illusion-casting power to appear somewhat different than she does as Molly Mayne. It gets improbable that Alan would not recognize her during the pageant.
This story also has a really good demonstration of the illusions she can cast, which are effective at decoying and delaying Green Lantern. As he tries to stop a non-existent tidal wave, the Harlequin steals the opal that was the prize for the contest. But Alan had planned for this, and the opal conceals a small camera, with which he hopes to learn her identity.
After the requisite scene that has the Harlequin aiding Green Lantern against her gang, she shows that she is no fool, returning the opal, but with the pictures destroyed.