Patty Duke, Dove Cameron Patty Duke, Dove Cameron

They laugh alike, they walk alike, at times they even talk alike. You can lose your mind: Veteran actress Patty Duke is once again playing it twice, this time on Liv and Maddie, the Disney Channel comedy about identical twins.

In the upcoming episode "Grandma-A-Rooney," Duke plays Grandma Janice, who visits the Rooney family to present her granddaughter Liv (Dove Cameron) with the "Porcupine of the Year Award." But Liv's sister Maddie (also played by Cameron) grows suspicious that it's Janice's twin, Great-Aunt Hillary (also played by Duke), who's actually visiting and pulling a switcheroo.

Duke, of course, is famous for playing look-alike cousins Patty and Cathy Lane on the 1963-66 ABC sitcom The Patty Duke Show. Duke later reprised the roles in a 1999 TV movie and more recently in a series of public service announcements for the Social Security Administration.

In some ways, Liv and Maddie, starring Cameron as mismatched twin teen sisters (one of whom returns home after a stint in Hollywood) is the modern-day successor to The Patty Duke Show."They say you should never meet your heroes, but Anna [Duke's real first name] is one of the kindest and most generous humans that I've ever had the pleasure to work with," Cameron says. "She taught me so much as an actor long before I knew her, and she continues to teach me even more as my friend."

Says Duke: "I waited for 50 years for this experience. It's everything I hoped for, most especially Dove."

Furthering the theme, the episode was even written by a real-life twin, Sylvia Green.

Here's a first look at Duke on Liv and Maddie.

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