Hilary Duff as The CEO

NEW YORK -- Starting this fall, Mary-Kate and Ashley Olsen -- the twin actresses-turned merchandising moguls -- will have some young celebrity company in store aisles.

Eighteen-year-old actress and singer Hilary Duff and 13-year-olds Dylan and Cole Sprouse -- twin actors and heartthrobs for the prepubescent set -- aim to mimic the success of the mary-kateandashley brand, with plans to bombard stores with a host of products from clothing to home decor. And experts say they expect there will be plenty of other young copycats hoping to turn their celebrity status into merchandising power among preteens and teens, as did the now 20-year-old Olsen twins, who parlayed their star power into a reportedly billion-dollar international brand, spanning cosmetics to clothing and rugs.

Duff, who shot to fame as the title character the TV series ``Lizzie McGuire," will be coming out with products aimed at preteen girls this fall. The merchandise, from clothing to room decor, will sell under the label Stuff by Hilary Duff in discounters like Wal-Mart Stores Inc. and midtier stores such as Kohl's Corp. They include hot pink fabric handbags and cropped black jackets.

The launch comes 10 months after Duff became chief executive and designer of her own fashion and lifestyle company. To help secure her footing, she hired Robert Thorne, the Olsens' former manager -- and until early last year the chief executive of Dualstar Entertainment Group, the Olsens' entertainment business -- to spearhead her merchandising empire. The goal: to generate retail sales worldwide of more than $1 billion in 2 1/2 years, according to Thorne.

Meanwhile, the Sprouse brothers, who star in the Disney Channel's ``The Suite Life of Zack & Cody," are targeting their merchandise at preteen and teen boys, with a new magazine called Sprouse Bros. Code, which hit newsstands this month.

Calendars will be out this fall at discounters like Wal-Mart and Target Corp. Next spring, there will be young men's clothing and grooming products like hair gel and deodorant sticks. Dualstar's chief executive Diane Reichenberger declined to name which stores will sell the products since discussions are still ongoing.

Company officials declined to offer sales projections for the Sprouse business or the mary-kateandashley brand.

``The minute I saw them they looked like a brand," said Susan White, brand manager for the Sprouse twins. She met them in 2002 and signed them as clients a year later. Last year, she introduced them to Dualstar, which forged an exclusive relationship as part of an overall goal to develop other personalities.

While building the Dualstar business, the Olsens themselves are further expanding their own brand, which got its big start with Wal-Mart seven years ago. This year, the twins expanded their accessories, cosmetics, and jewelry offerings with Claire's Stores Inc.