True cases of people suffering from multiple personality disorders are among the most harrowing encounters most of us could ever expect to face this side of the supernatural. The idea that a person is not just “acting” like wildly different people, but wholly inhabited by several distinct personae whom they believe themselves to be — utterly — is just chilling.

So it’s a shame that the movies have rendered such rarities humdrum and routine. But actors just love the idea of slinging several accents and wearing several guises during the course of a film. Halle Berry certainly did. That goes a long way in explaining “Frankie & Alice,” a long-shelved 2010 melodrama, “based on true events,” with six credited screenwriters (with two other writers credited for the story) and nothing new to add to the genre.

Frankie is a good-looking, streetwise stripper in 1970s Watts, Los Angeles. The veteran of the gilded cage/take-it-off club tells a newcomer that she just lets “the music take me, like I’m watching myself from the outside.” It’s how she copes.

But the stage isn’t the only place she does that. All sorts of things can set Frankie (Berry) off. And when she goes, she becomes a drawling, hellfire and brimstone quoting Southern belle, railing about “idolatry” and “covetousness” and the coming “wrath of God.”

Which is a real buzz kill for her love life. That, and her tendency to turn violent and then black out.

One such episode puts her in the reluctant care of free-thinking Dr. Oswald (Stellan Skarsgard). He’s wondering if it’s her drug use.

“Frankie got rules,” Frankie says. “No Smack. No Blow. No Speed.”

And then the doctor meets the other woman in Frankie’s head.

“In mah experience, doctors are most always TIREsome bores,” “Alice” acidly drawls. “Or drunks. Which are you, Doctor Oswald?”

Alice tests at a lower IQ, writes with a different hand and feigns racist, Anti-Semitic leanings. The jazz-listening research scientist turned clinician is fascinated.

“Frankie & Alice” is a soapy period piece that hits all the usual mileposts in filmed versions of such stories. Frankie refuses to admit she has a problem, but we see flashbacks that hint at the “reasons” for the disorder and meet her protective mother (Phylicia Rashad) who knows more than she lets on.

Skarsgard plays Oswald with a sort of offhanded good humor, but the doctor is a stock “type.” And the Oscar-winning Berry treats this showcase for what it is — an acting exercise, and a fairly broad one. She can and has pulled off versions of these women she’s playing in other films. And the 32 year-old stripper in a strip-club opening has a hint of “See how well-preserved I am?”

Yes, she is. Of course, she filmed this vanity project almost five years ago, which tends to undercut it as a bid for more Oscar-worthy roles. That and her performance of this unoriginal script.

MPAA Rating: R for some sexual content, language and drug use

Cast: Halle Berry, Stellan Skarsgard, Phylicia Rashad

Credits: Directed by Geoffrey Sax, screenplay by Cheryl Edwards, Marko King, Mary King, Jonathan Watters, Joe Shrapnel, Anna Waterhouse. A Lionsgate release.

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