SIMPSON SISTERS HIT SOUR NOTE!

Rivalry explodes as they plot dueling musical comebacks

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SINGING sisters Jessica and Ashlee Simpson have long had a competitive relationship — but their rivalry is turning nasty as both plan their musical comebacks at the same time, sources gab.

Pop punk has-been Ashlee, 39, followed millionaire fashion mogul Jessica, 44, back into the studio — after both gals took a 16-year break from recording!

“Jessica loves Ashlee, but it rubs her the wrong way that her own sister is planning her comeback at the same time and will likely take some shine off her return,” a pal dishes.

“Ashlee knows Jessica has been working on a new album, and it got Ashlee to thinking maybe she should try to gain a foothold in the music business again as well.”