CALABASAS, Calif. (AP) — One of the world's most famous motorcycles — the star-spangled "Captain America" chopper from "Easy Rider" — is hitting the auction block.

Or not.

As the skeptical Billy from the 1969 counterculture cult film might have asked: "What's the reality, man?"

The red, white and blue, chromed-out Harley-Davidson to be auctioned off late Saturday in Calabasas comes with certificates of authenticity, according to the auction house, Profiles in History.

More than one version of the bike was built for the movie but according to the auction catalog, the one for sale is the only one that survived.

According to the catalog, it was used in the climactic crash sequence at the end and restored by Dan Haggerty, who had a bit part in the film and vouched for its authenticity. Peter Fonda, who played Wyatt and rode the bike in the movie, also vouched for its authenticity, according to the auction house.

The seller, Michael Eisenberg, also has a letter from the National Motorcycle Museum in Anamosa, Iowa, which displayed the bike for 12 years, saying Eisenberg's is the only surviving "Captain America" bike.

But another collector, Gordon Granger of Texas, says he owns the authentic chopper and also has a certificate signed by Haggerty to prove it.

Haggerty acknowledged to the Los Angeles Times (http://lat.ms/1sQi3b6 ) this week that he authenticated and sold two "Captain America" bikes.

Now Haggerty says just one of the bikes is legitimate, and it's Eisenberg's — the one going up for sale with a $1 million minimum.

The dust-up could affect the auction price, Eisenberg said.

"I'm concerned. If you throw enough rocks at something, it casts a shadow of a doubt about something," he told The Associated Press. "I'm damaged."

For his part, Fonda says he has no idea which bike is the real one.

"There's a big rat stinking someplace in this," the 74-year-old actor, who co-wrote "Easy Rider," told the Times.

Eisenberg, a Los Angeles real estate agent and collector of Hollywood memorabilia, bought his chopper earlier this year from John Parham, a Midwestern motorcycle parts magnate who had purchased the bike from Haggerty 12 years earlier.

Haggerty did not deny that he also signed Granger's authenticating documents. He now says he signed something that simply was not true.

"That was my mistake," Haggerty said. "It's not the real bike."

Granger, furious at the prospect of this weekend's auction, insists he owns the genuine article.

"They know damn well they don't have the real bike," Granger said. "I own the original remaining "Captain America" bike. The one to be auctioned is a replica."

The chopper features a forward-angled front wheel and handlebars, fishtail exhaust pipes and a teardrop-shaped gas tank where the movie's protagonists stashed their cash. It was designed with input from Fonda who insisted on it being decorated with the American flag.

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Information from: Los Angeles Times, http://www.latimes.com