Garry does Larry

''It's not about Johnny,'' Shandling insists, although he admits that ''some of it is similar to what goes on at The Tonight Show. But it's also from my experiences on every talk show I've done. I'm sure people will read things into some of these shows. Some of that will be accurate. Some of it won't.''

Shandling has been getting offers to set up his own late-night desk and couch for years; Tribune Entertainment execs preferred him over Dennis Miller for its now-canceled talk entry. But five years ago, even as he was immersed in his last violation of TV reality, the fourth-wall-bashing It's Garry Shandling's Show, he started toying with the notion of a make-believe talk show that would let the audience see what goes on off camera.

''I just think that, for me, doing a real talk show would have been unfulfilling,'' he says, leaning back in his chair and rubbing his eyes, as if the very thought of it leaves him exhausted. ''There were nights when I guest-hosted for Johnny where I would walk off the stage and go, 'Man, why would I ever want a job where I'm forced to talk to people that I would never want to talk to in real life?' I mean, some nights it's incredibly fun, when you get to talk to Sugar Ray Leonard or someone like that. But a lot of nights you'd just be faking it.''

Shandling kept this idea of playing a talk-show host to himself until last year, when HBO president Michael Fuchs asked if he'd be interested in developing a comedy series about, of all things, a fictional talk show. ''As a matter of fact,'' Shandling told Fuchs, ''I know just how I'd do it.'' And, with the real-life talk-show wars raging more intensely each day, the timing couldn't be better. ''We're taking advantage of the fact that there's been so much coverage lately, especially since Johnny left,'' Shandling says. ''Everybody in the country is so aware now of what's going on.''

Even when he's not on camera, Shandling (who wrote for such sitcoms as Sanford and Son and Welcome Back, Kotter before breaking into stand-up in 1975) remains on the set during tapings, watching the monitor, working closely with Jim Kantrowe, a Tonight Showassociate director for 19 years, who supervises Shandling's/ Sanders' on-air scenes. As the star, producer, and principal writer, Shandling takes responsibility for every script change, camera angle, and editing decision. The pressure shows.

''It's a very ambitious show and I do get incredibly drained and edgy,'' he admits. ''That's one of the big differences between Larry and me. He's in a more isolated position and has a producer who shelters him from the daily goings-on of the show as much as he can. I'm not sheltered from anything.''

As he steps on stage later, his torn jeans traded in for a suit and tie, Shandling gets somewhat more animated. Preparing to perform five Sanders monologues in a row, he tells the audience, ''I know this is all a little disjointed.'' But so attuned to talk-show ritual are they that with no instructions, they clap at all the appropriate times-even applauding the nonexistent band at the moments when music will later be added.

At the close of each monologue, Shandling—no, Sanders—deliberately (or perhaps not) evokes the memory of ancestor Carson's golf swing with his own trademark gesture: Extending an imaginary remote control, he cheerfully admonishes his viewers, ''Don't flip around.''

But then which viewers is he talking to? The ones watching Garry? Or the ones watching Larry? Or...