Behind an unlabeled door in a building along Eastlake Avenue East lives the Marvad Corp., a lucrative online empire of Internet pornography sites that have made the owners rich men.

And until about a week ago, the unobtrusive office, in the same building as a chiropractor’s office, was home to one of the few copies of a videotape showing Paris Hilton, the 22-year-old hotel heiress and reality-TV phenomenon, having sex a few years ago with her boyfriend at the time.

“You walk in there, you’d think it’s an insurance office,” Kevin Blatt, Marvad’s publicist in San Diego, says with a laugh.

As anyone who regularly watches the E! cable channel knows, Hilton’s ex-boyfriend, Rick Solomon, best known for being married briefly to actress Shannen Doherty, sued Marvad in federal court in Los Angeles last week, alleging the company had no right to post the video on the Internet and charge people about $29.95 each to see it.

In turn, Marvad sued a man named Donald Thrasher, 33, an acquaintance of Solomon’s who somehow got a copy of the tape and sold it to Marvad for $50,000 plus royalties. Marvad contends Thrasher had falsely claimed to have rights to the X-rated video.

Also, Solomon has sued Paris Hilton and her family, alleging they defamed him by portraying Hilton as a rape victim and unwilling participant in the on-camera sex when she was 19.

Marvad finally agreed to give the tape back to Hilton and not put it on the Web after all. But there reportedly are other copies out there. And yesterday, tabloid-news reports said there may also be a tape of a different Paris Hilton sexual encounter.

The series of events has become a titillating controversy-of-the-moment that the operators of Marvad say they would rather not deal with.

“They’re the complete opposite of what people think a Web pornographer looks like,” Blatt says of Marvad. “They’ve realized the mileage they’ve gotten out of the publicity. But these guys are very ethical, very honest about what they’re doing. And for them it’s not even about the porn. It’s about the business.”

The Web pornographers, in this case, are two 33-year-old longtime buddies, Roger G. Vadocz, who lives in Tampa, Fla., and Brian Marchlewicz of Seattle.

Information about the pair is limited to the words of their publicist and a few references on Internet sites devoted to pornography. They generally do a good job of staying out of the public eye.

Blatt describes Marchlewicz as the technical brains, while Vadocz has the looks and the marketing skills. They have made lots of money, Blatt says, without saying how much.

“They’ve done very well over the years,” Blatt says.

In fact, he boasts, the pair are among the few tech-porn pioneers who have kept their ledgers in the black through the years. While others, including friends in the industry, were sued, prosecuted or bungled their way out of business, the pair stayed ahead of the game, says Blatt.

The two, both from California, met in their 20s in Seattle, Blatt says. They were business savvy. At least one of them had a good working knowledge of the telephone industry. They apparently didn’t mind pornography, so they started making their fortune running phone-sex lines, Blatt says.

In the mid-1990s, they began operating an Internet porn business that prospered and led to a string of different sites. “Low overhead and high profit,” Blatt says. All the owners have to do is buy videos and photographs from other people, put it on the Web sites and cash the checks.

Nowadays, Vadocz portrays himself as a playboy. One Web site lists him as the No. 7 “most eligible bachelor” among a list of other Web-porn operators because of his wealth, dimpled good looks and ability to date porn princesses.

“Roger lives the lifestyle,” Blatt says. “He’s got the most amazing wardrobe you’ve ever seen.”

Blatt won’t say much about Marchlewicz, except that he’s a married-with-children kind of guy who doesn’t like having his name in the papers. Records show he married his 31-year-old wife last year.

But when the pair announced that they would put the Hilton video on their site, they couldn’t avoid the attention.

Blatt insists Vadocz and Marchlewicz have been “very cooperative” with Hilton and her family.

The Hilton family attorney in California, David Rudich, would agree only that the company owners had indeed “settled their differences with Paris Hilton” but wouldn’t discuss the matter further. Hilton released a statement Monday saying she was “embarrassed and humiliated” that her intimate life would become public.

Marvad’s Seattle attorney, Derek Newman, says the company has indeed destroyed its copies of the tape. “Marvad was duped,” Newman said.

Meantime, back at the previously anonymous office on Eastlake, the folks at Marvad still are doing what they do best: publishing porn.

“Everybody loves to watch a car wreck, and this is a big car wreck,” Blatt says cheerfully. “But we’re the victims here, because we’re out $50,000 and the public never got to see the tape.

“And frankly, I think this is the best thing that could have happened to Paris Hilton’s career.”