The college basketball doubleheader as an institution may have had its heyday, but the concept lives. In decades past, at the old Madison Square Garden in particular, teams would assemble -- sometimes six because the Garden often put on college tripleheaders -- and basketball junkies would come streaming to root on the local heroes, especially when they were matched against out-of-town Enemies. It was war, or so it seemed.

Attending a college basketball doubleheader has its own peculiar feeling, a distinct state of mind. It offers both a casualness and intensity that cannot be duplicated by a single game. One can arrive unconcernedly late for the first game and vent passion in the nightcap if that's where allegiance resides, or hang around for, say, a half of the second game if the first is all that matters. For purists, it all matters.

Thursday night at the Patriot Center in Fairfax County, an experimental twin bill, evoking memories of winters past, was served up: American U.-James Madison followed by Navy-George Mason. While the threat of snow held the crowd to 5,222 in the 10,000-seat arena, that intrepid group included all sorts of college basketball purists: an ex-pro basketball star, high school coaches, an ex-college coach, scouts, former college players and a hundred gym habitues recognizable by their own familiar routines of talking animatedly among themselves during every break but always riveting on the court action.

"We just wanted to see how this would work," said Jack Kvancz, George Mason's athletic director. "We appreciate AU giving up a home game and playing here, and when their place is built we'd be happy to reciprocate."

When it comes to college doubleheaders, Kvancz has a history. He played in the mid-'60s on two Boston College NCAA tournament teams, when getting into the NCAA tournament was a feat. But just as vivid in his mind are doubleheaders at the Garden and the Palestra in Philadelphia. With BC, Kvancz was among The Enemy in New York and Philadelphia.

A typical Palestra doubleheader, Kvancz recalls, would be Temple-La Salle in the first game, BC-St. Joseph's in the second. "If you were playing the second game and you were from out of town, you'd better be ahead by the half," he said, "because you weren't going to get any calls down the stretch and the crowd was unmerciful."

Similarly, BC drew wrath at the old Garden (actually, that was the third Garden, the present one being the fourth). In one BC-St. John's affair, Kvancz helped lead a come-from-behind rally only to miss a crucial free throw near the end that, in his inalterable thought on the matter, cost BC the game. "I'm still trying to forget it," he said.

"The classic basketball night at the Garden," said John F.X. Condon, the public address announcer of college games there since 1950, "was when City College won the NIT after winning the NCAA. That never happened before, and it never will happen again.

"City College and St. John's were the giants, but St. John's playing any local team was a big rivalry. NYU-Georgetown was a rivalry. Holy Cross and Providence would come in . . . "

While the Patriot Center doubleheader was not to be confused with some of those ancient matchups that seemed to shake the earth for some forgotten reasons, the assembled area teams signaled only good for the state of the game in and around Washington -- and it could have been the start of something special. What AU diehard wouldn't hang around for a glimpse of Navy's 6-foot-11 David Robinson? Staunch Mason followers could come early to "scout" American in preparation for tonight's Mason-AU game.

The surroundings measured up well against notions of a college basketball doubleheader's ambiance. The new Patriot Center provides an excellent view of a basketball game, with its polished green and yellow seats pitched close to the court. The green-costumed "Mason Maniac" was the kind of adornment unknown in Joe Lapchick's days, but he or she agreeably added to the second-game milieu, as did the George Mason band. Say what you will, but the second game is the attraction, if for no other reason than the home team is in it.

There's something pleasantly illusory about teams that play in second games. They take the court by streaming out single file with full enthusiasm as sweaty opening-game players are dragging themselves away. In these moments of transition from game one to two, the new teams somehow seem bigger and more capable than the opening teams.

Before the second game, the George Mason NCAA champion women's soccer team was introduced to sustained applause, which added to the correct impression that a lot was going on. Then Navy's Robinson went to work with an assortment of stuffs: he has heavy-duty slams that dip the rim and gentler ones that ripple the nets. A decisive force.

By the half or midway into the second half, some fans climbed over others who wouldn't leave for anything short of the final horn, and headed for their cars in the big lots. They had sampled both games of a doubleheader and, satisfied, still could beat the snow home.