I don't know where you're planning to spend the month of October, but John P. Rowan of Silver Spring is going to spend it on pins and needles -- courtesy of a computer.

"Returning from a weekend trip last Monday," John writes, "I found a slip in my mailbox saying there was a certified letter waiting for me at the neighborhood post office." It was from the Maryland Department of Transportation. It wasn't good news.

"NOTICE OF CANCELLATION," the letter began. "You have falsified the application and obtained a Maryland driver's license while your privilege is withdrawn in another jurisdiction."

The letter went on to explain that, according to computer records, John's license to drive had previously been suspended by the state of Tennessee. Therefore, John had lied on his Maryland application when he said his privileges had never been suspended or revoked. As a result, his license would be canceled on Sept. 30 unless John wrote to request a hearing.

John has done so, and it is at least even money that he will never have to spend so much as a day without a valid license. Still, John is not sure he will ever be able to clear his name, even if he keeps his driving privileges.

The problem is that there's another John P. Rowan.

The other John lives in Nashville. Tennessee John was born exactly one year before Maryland John (Sept. 25, 1956 and 1957, respectively). The two men have the same eye and hair color (blue and brown), and they weigh the same (l90 pounds). Only in height are the two Johns significantly different. Tennessee John is 6-foot-3. Maryland John is 6-foot-1.

Maryland John has obtained the driving record of his namesake, and it is not spotless.

Tennessee John has been cited four times for speeding and in each case was ordered to attend a driver improvement session. Tennessee John's license was revoked by the state of Tennessee in June. Apparently, a computer took one quick electronic look at "Sept. 25," brown hair and blue eyes and decided the two Johns had to be the same person.

"I've never been to Tennessee," writes Maryland John. "The only driver's license I've had besides Maryland's was in the District."

Even past masters of mistaken identity like Gilbert and Sullivan would know what to do in this case. Have the Maryland DOT write to the Tennessee DOT and straighten it all out. Then the two Johns could meet at center stage, sing a duet with their arms wrapped around one another, take a couple of curtain calls and call it a day.

Sadly, it's not that easy. In Maryland, you're guilty till proved innocent, DOT staffers told Maryland John. He would have to arrange for Tennessee's DOT to unscramble the mess. Maryland DOT wouldn't do it for him.

"At this writing," concludes Maryland John, "I don't know how difficult it's going to be to clear myself. A 'clearance letter' is supposed to be on its way from Tennessee . . . . I'm hoping that will be the end of it."

But even if it is, John won't know until the end of October, since the bureaucracy takes at least four weeks to grind out a correction of this sort.

Meanwhile, will Maryland John's driving record forever say that he once falsified his license application? Will his insurance be in force if he has an accident while waiting for the Tennessee letter to arrive? Will John have to reapply for a license, and pay a second fee, once the Tennessee letter arrives at Maryland DOT?

Shame these questions even have to be asked. As Maryland John notes, all he has ever done wrong was to be "born a year after a bad driver."