IT'S TIME FOR another actor smackdown - just in time for Christmas.

Stephen Baldwin, the youngest of the acting Baldwin brothers (and perhaps the nuttiest), has sued Kevin Costner over investments in a device that BP used in trying to clean up the Gulf of Mexico oil spill.

The federal suit filed in New Orleans by Baldwin and his friend, Spyridon Contogouris, claims Costner and his business partner Patrick Smith duped them out of their take from an $18 million deal for BP to purchase oil-separating centrifuges from a company they formed after the April 20 spill.

BP ordered 32 of the centrifuges, which separate oil from water, and deployed a few of the devices on a barge in June, three months before the gusher was capped.

Baldwin and Contogouris, owned shares in Ocean Therapy Solutions, the company that marketed the centrifuges to BP.

But Baldwin and Contogouris claim they were deliberately excluded from a June 8 meeting with Costner, Smith and BP executive Doug Suttles. At the meeting, the suit says, Suttles agreed to make an $18 million deposit on a $52 million order for the 32 devices.

Baldwin and Contogouris said they didn't know about the deal when, three days later, they agreed to sell their shares of the company for $1.4 million and $500,000, respectively.

They say they were entitled to a piece of BP's deposit. Instead, their suit claims that Costner and Smith "schemed" to use the deposit money to buy their shares.

The suit seeks unspecified damages.

Are royal images a coin job?

Brits who care about all this royal-wedding stuff were outraged yesterday because the Royal Mint released a commemorative coin featuring portraits of Prince William and Kate Middleton, but the likenesses looked more like Al Gore and some anonymous chubby chick.

Coin describers said Kate appears plump in the face and lips, and has bags under her eyes.

Available in silver or gold, the 5-pound ($7.70) denomination coin costs 9.99 pounds ($15.40).

You know what they say, the coin always adds ten pounds.

"This coin is of historical importance, to get it so wrong seems ridiculous," Ingrid Seward of Majesty magazine told Britain's Sky News.

The Royal Mint said the portraits had gone though "a rigorous approval process" and both Queen Elizabeth and William had given their consent to the design.

"The Royal Mint has been recording historical events for over 1,100 years," said the Mint's Dave Knight.

Unfortunately, the same fellow seems to be doing the engraving.

Tattbits

* A spokesman for the California Department of Public Health confirmed the agency was conducting an investigation at the Betty Ford Clinic, but spokesman Ralph Montano could not confirm that the inquiry was related to Lindsay Lohan.

Detectives are investigating Lohan for misdemeanor battery at the request of a Betty Ford Clinic worker who was involved in a fight with Lindsay about 1 a.m. on Dec. 12.

Lohan's oh-so-busy attorney, Shawn Chapman Holley, has declined to comment on the incident, but said it was Lindsay who called police.

The Betty Ford worker later conducted an on-camera interview with TMZ.com, which also posted an e-mail the worker apparently sent to supervisors after the fight. The woman, identified by TMZ as Dawn Holland, was promptly fired by Betty Ford.

Criminal defense attorney Steve Cron, who is not involved in the case, said Betty Ford, which described the Lohan incident as the first time in 28 years that it had a breach of patient confidentiality, could face a civil fine.

* The rock-catalog musical has been a staple in recent years (thank you, "Mamma Mia") and billboard.com reports another one is in development.

From Air Supply.

Yes, the treacly guilty-pleasure pop duo (Russell Hitchcock and Graham Russell), celebrating its 35th anniversary, is "working with some people in New York . . . producers and a playwright," about the possibility of turning Air Supply's work into some kind of musical story, Hitchcock said.

"All Out of Love"? "Here I Am"? "Even the Nights Are Better"?

It's like a Tattle AM radio nightmare.

* A man wearing a Bob Dylan backstage pass who ordered 178 pizzas from a Massachusetts pizza parlor but never picked them up has agreed to pay for his pies.

A lawyer for the New Jersey man says his client is a "decent enough" guy with no record, who felt bad about the prank.

"Decent enough?" That's high praise.

Workers at Antonio's in Amherst stayed until 5:30 a.m. on Nov. 20 making the pies. The man ordered them shortly after a Dylan concert at nearby UMass.

He said he would return in several hours and deliver them to Dylan's crew. He never returned and the manager called police.

* Crown Publishers has announced that Daniel Domscheit-Berg, a/k/a Daniel Schmitt, a/k/a the former spokesman for Wikileaks, has a book coming out in February.

The book is called "Inside Wikileaks: My Time with Julian Assange at the World's Most Dangerous Website." Crown says it "will reveal the evolution, finances and inner tensions" of the organization that posts confidential government documents.

Schmitt left WikiLeaks three months ago over personal, ethical and political differences with Assange and announced plans to launch Openleaks.org, to start in early 2011.

(Note: this is not a site for pee fetishists.)

Governments should leak his entire book on their websites.

* And on that joyful note, Merry Christmas.

Daily News wire services contributed to this report.