* Brothers, separated as babies, look for the killers of their parents as adults.
CAST: Jean-Claude Van Damme, Geoffrey Lewis
DIRECTOR: Sheldon Lettich
RATING: R (language, nudity, sex, violence)
RUNNING TIME: 105 minutes WE'VE SAID this before: Jean-Claude Van Damme is a nice guy. So nice that you hate to say that his newest film, ''Double Impact,'' is a laugh.
It doesn't mean to be. Part of the time it wants to be funny, but overall, it means to be taken seriously, as an action film with a sense of humor. The trouble is, you keep laughing all the way through.
Bones are broken, and you laugh. Bullets are fired, bodies fall, and you laugh. Some of the actors try to act, and you laugh at that, too.
It's a pity. Van Damme is trying to broaden his scope with this film. As Arnold Schwarzenegger has done, Van Damme is trying to move away from the heavy action film to the action-comedy film.
He's not as good at this as Schwarzenegger, but if we give him time, maybe he'll make it. It took time for Schwarzenegger to make the transition, too.
Van Damme plays twins in the film. Hence, the reason for the title. As infants, the brothers lose their parents. Their father, involved in the construction of a tunnel connecting Hong Kong with mainland China, was "erased," along with his wife, by two of his business partners, who wanted all the profits.
The twins are saved, but separated. One is taken to an orphanage; the other is cared for by the family bodyguard.
After being reunited years later in Hong Kong, the boys learn why their parents were killed and go after the murderers who have, among them, a lesbian martial arts expert. She, too, makes you laugh.
The killers also employ a lovely blonde who, initially, will not believe what she has heard about her bosses. When she is convinced, she joins the brothers.
She has sex with one, and again, we laugh. Perhaps we shouldn't, but in our defense, we might say that the sex sequence, in this particular film looks like something a more ambitious couple might do in an aerobics class, in front of an appreciative audience.
''Double Impact'' was filmed in Hong Kong, so it has that going for it. The special effects are quite good, too, and the movie zips along. Unfortunately, it is funnier than it means to be.
''Double Impact'' opens here today. We fervently hope that Van Damme achieves the kind of stardom he wants, even deserves. The new film, however, is more a detour than a direct route to that goal.