IN THIS computerized age, machines can make errors more complicated than people could ever devise. So checking your dinner bill isn't enough. You need to check your monthly credit card statements to be sure you haven't been charged twice for the same meal.

Recently two readers alerted me to the problem. The first sent a bill from Quigley's that showed up on one MasterCard statement twice, the identical amounts having been charged one Friday and the following Tuesday. When I called the restaurant to find out how this mistake could have happened, the manager on duty, Jeff Maguire, was at a loss to explain. He said that occasionally a charge gets posted twice on the same day, but he's never heard of one being duplicated several days later.

At Fred's Place in Arlington the same charge was duplicated 11 days apart on a Visa bill. Owner Fred Berman said he had no idea how that could happen, but it wasn't the first time. "We deal with 1,200 to 1,400 customers a day," he said, and estimated that double billing occurs once every year or two.

YEARS AGO, 15th Street was the site of a much-loved German restaurant. And next week, just a block south of where it stood, once again a German beer hall will appear. The Old Ebbitt Grill is celebrating Oktoberfest Sept. 27 to 29 in its atrium. At 6:30 p.m. each of those evenings the atrium will be set with long tables and enlivened by German bands and variety acts. The menu will reflect the event with the likes of schnitzels, sauerbraten and smoked pork plus, of course, German beers and wines.

Other Clyde's restaurants -- 1789, The Tombs and Clyde's of Tysons Corner -- will also feature German specialties next week, while Clyde's of Georgetown will celebrate its Oktoberfest Oct. 4-6.

IF YOU NEED evidence that home cooking is extinct, look at Lawson's, the fancy food shop on Connecticut Avenue just south of Dupont Circle. When it first opened, it featured exotic produce -- beautiful vegetables, elegant fruits, ingredients you might need to cook a grand dinner party. Gradually, though, the produce section faded and the lush variety dwindled to just a few fruits to eat by hand. Now the space is taken by a "gourmet salad bar." Today's Lawson's customers need no tool more serious than a fork.

While the salad bar includes greens and a few plain cut-up vegetables, most of it is prepared cold dishes. By salad bar standards it is expensive -- $4.99 a pound -- but the choice is broad, including high-quality versions of corn salad, potato salad, couscous, several pasta salads from Oriental to Italian, black-eyed pea salad, and chunks of plain grilled chicken. In fact, it looks like a serve-yourself arrangement of Lawson's carryout-foods display case.

RESTAURANT NORA and the City Cafe have always served food that's been as organically grown, as natural, as real as possible. But I've thought they carried the avoidance of plastic too far by taking no credit cards. At last they have seen the light, and for the first time Nora and City Cafe will accept payment by Visa and MasterCard.

In addition, Nora has done away with its acoustical tile ceiling to reveal the space above it. The result, says owner Nora Pouillon, is more countrified than ever.

Phyllis C. Richman's restaurant reviews appear Sundays in The Washington Post Magazine.