The radical idea of slotting the same episode of hit TV series like “Home Improvement,” “Seinfeld” and “60 Minutes” twice in the same week has begun to polarize network executives and their brethren in the ad agencies and production houses.

The new United Paramount Network has made showbiz history by being the first network to double-run, on a regular basis, its signature series, “Star Trek: Voyager” – thus being able to sum the two ratings.

The question is: Will the Big Three and Fox follow suit? CBS and Fox say maybe, NBC says probably not and ABC says no way.

David Poltrack, executive VP of CBS, says, “We’ve told our sales department to look at the option of experimenting with a second run” of existing TV series. The experiment could begin, he continues, with a non-primetime series, such as “The Late Late Show” with Tom Snyder, and then proceed to a primetime show that’s “nearing the end of its run.”

Larry Hoffner, head of sales for NBC, said he’d consider double runs only if the second run of a hit series like “Seinfeld” harvested a better rating in its time period than the first run of an original series, and NBC could sell the combined rating of the two “Seinfelds” for a higher price than each of the two could fetch if sold separately.

One Fox exec says Fox would be more inclined to take the second run of a primetime series in a fringe time period like latenight or early evening on Saturday, where the competition wouldn’t be as tough as primetime.

ABC is the one network that, at least for public consumption, is closing the door. “We have no plans to change our entire programming strategy just because Nielsen is allowing UPN to double-run ‘Voyager,’ ” says Peter Chrisanthopoulos, exec VP for ABC.

Chrisanthopoulos would endorse the view of Paul Schulman, president of his own media-buying firm, who evokes the concept of the must-see “appointment show.” In this analysis, a hit show becomes an event every week, riveting the attention of viewers because they know the episode will be the subject of discussion over coffee at the office the next morning.

“While you’re watching an appointment show,” Schulman says, “you won’t take phone calls, you won’t leave the room.” Advertisers pay through both nostrils to get a 30-second spot on an appointment show.

But if that episode is going to be available a few nights later in repeat, people won’t make the effort to see the first day-and-date run. Erosion in the rating of that first run, Chrisanthopoulos says, would damage the earning potential not only of that show but of the series that lead into and out of it.

If the networks are divided over the double-run issue, the production community also is trying to figure out what it all means.

Through a spokesman, Brandon Tartikoff, chairman of New World Entertainment, says it’s inevitable that the broadcast networks will go to double runs of their primetime series because TV syndicators and cable networks like USA have done it for years. He adds that he’d love to pocket the increased license fees the networks would have to fork over for the additional runs.

But more production executives echo the hostility of Fred Silverman, an active TV producer (“Diagnosis Murder,” “Matlock”) who has been head of programming at each of the Big Three. By scheduling two runs of the same episode within three to five days of each other, Silverman says, “The networks would end up turning their valuable primetime real estate into a parking lot. And they’d drive a lot of producers out of business.”

Although he’s considering the double-run strategy, Poltrack says CBS would set it up with a great deal of reluctance. As a scheduling ploy, double runs would be more defensive than offensive, triggered by “the reinventing of the rules by Nielsen to satisfy the marketing needs of the United Paramount Network,” as Poltrack puts it.

For the first time ever, Nielsen has agreed to give UPN, which it calls “an emerging network,” the right to add together the ratings for two separate runs, within the same week, of “Star Trek: Voyager,” and to publish the resulting figure – called a GAA, for gross average audience – in the weekly ratings booklet known as the pocketpiece.

Waving the GAA number around like a winning ticket in the Irish sweepstakes, Paramount salespeople have parachuted into Madison Avenue to harvest premium ad rates for “Voyager’s” 30-second spots.

Bill Croasdale, head media buyer for Western Intl., says advertisers have ponied up a strapping $160,000 for a 30-second spot on the syndicated “Star Trek: The Next Generation” and “Star Trek: Deep Space Nine” because “we recognize that the only way Paramount can make out on the $2 million an episode it costs to produce these shows is to sell a double exposure. UPN has created a similar policy with ‘Voyager.’

“And if it works for UPN,” he continues, “there’s nothing to prevent Fox or the other networks from selling a second run of their primetime series. I’m hearing the rumblings, and everybody in the advertising community will have to start looking at how these double runs will impact our guarantees.”

But ad agency execs are preparing to disabuse the networks of the notion that they’ll pile up a windfall of advertising dollars by scheduling two runs each week of their hot shows. “The networks would end up diluting their franchise, which is the first run of an original-series episode,” says Steve Sternberg, the top media buyer at Bozell, echoing the comments of a number of his peers.

That possibility worries Poltrack as well. Using ABC’s “Home Improvement” as an example, Poltrack says that if the 20.1 rating it chalks up Tuesday at 9 p.m. slid to a 15 rating because of a second run on Saturday, “that falloff could bring the whole night down for ABC.” “Home Improvement” is a tentpole for the two-hour sitcom block that starts with “Full House” and “Me & the Boys” from 8 to 9 and wraps up with the third highest-rated series in all of network primetime season-to-date, “Grace Under Fire,” at 9:30. (“Home Improvement” and “Seinfeld” are tied for No. 1.)

What it all boils down to, says Chuck Bachrach, senior VP of the West Coast ad agency Rubin Postaer & Associates, is this: “The green-eyeshade people have taken over the networks and are basing their decisions on what’s good for the bottom line.”

If double runs start creeping onto the networks’ schedules, Bachrach, who refers to the Big Three as “dinosaurs,” says, “They’ll just be speeding up their inevitable march to extinction.”