Most people read only one paper a day, but there is a gaggle of news groupies who compare newspaper coverage for fun and occasionally are lucky enough to get paid to do it.

Reading the Sept. 27 Post, I was surprised to come across a story headlined, "Soviet Diplomat With KGB Ties Defects to U.S." -- surprised that the head was only a single column in small-size type and that the story was only five inches long.

Other Post-watchers were also surprised, because some had seen a Sept. 25 front-page Washington Times article headed, "No. 5 Man for KGB Now Singing to CIA?" and a half-page spread by Ralph De Toledano in its Commentary section the same day with the headline "The Missing KGB Link."

The Washington Times coverage, while not igniting fires at The Post, did alert The Los Angeles Times Washington bureau to begin checking. Ronald Ostrow, who covers Justice and does investigative reporting, and Doyle McManus, who covers state and national security, started digging. Mr. Ostrow said, "We had some things, then we saw The Washington Times story and the column. . . . It's a very dicey area. We had the usual problems, but we got enough confirmation and additional detail from U.S. sources and we went ahead."

The result was a 15-inch story, which led the Los Angeles Times front page on Sept. 26. The same story appeared on the Los Angeles Times-Washington Post News Service ticker at 8:28 p.m. EDT Sept. 25, but The Post did not use a line of it.

The next day Post national reporter John Goshko patched together its five- inch report, and the editors stuck it way back on page A22. On the same day, The New York Times had a 20-inch report by Stephen Engelberg from Washington beginning on page 1 -- obviously the paper considered the defection of major importance.

In preparing their report, The Los Angeles Times reporters pulled up on their electronic information retrieval screen some wire service reports orignating in Italy in August, which told of rumors circulating about a high-level Soviet defection to the West, but did not have specifics as to name or position. The Los Angeles Times report noted the earlier Washington Times story that identified him as the No. 5 man in the Soviet secret police.

Where were The Post editors on all this?

Their foreign desk "had a couple of vague reports from the Italian press that something had happened in Rome," said Richard Weintraub, deputy foreign editor, but the reports, besides being vague, "were at odds with each other." Assistant Foreign Editor Al Horne was checking sources in Washington and querying correspondents abroad, but immediate results were not forthcoming.

Difficulty in obtaining such information in Washington or abroad is understandable -- governments don't put out press releases on spy shifting -- but failure to follow up on front-page material in another newspaper or to use information available from a newspaper brother, The Los Angeles Times, suggests an internal problem.

Last week, Robert Kaiser, assistant managing editor for national news, wasn't eager to discuss the matter, but he declared, "On a very sensitive subject we don't put things in the paper that we haven't verified ourselves. We still don't know that he is one of the top five in the KGB. He doesn't show up on any list we have seen."

"It's an extremely murky story, but we're working hard on it now," said Mr. Kaiser, a former Post Moscow correspondent.

Editors who suspect all news appearing in another publication as ideological may run the risk of overlooking significant news. Editors who spike 15-inch reports from newspaper partners, such as The Los Angeles Times, bury a chance to recover from such error. Post editors were slow -- and late -- getting started. A five-inch story two days late is more an admission of that than adequate coverage of a major news development.

This is one time when "The Russians are coming, the Russians are coming" was literally true. An important Russian did come over.