There must have been something in the air.
"The joke is I used the name Harry Potter in one of my Henry-and-Sunday stories," Clark says.
Henry is Henry Parker Britland IV, a former U.S. president, married to Sandra "Sunday" O'Brian, a congresswoman. Together, the sophisticated couple get into scrapes and solve mysteries, a la Dashiell Hammett's Nick and Nora Charles.
Clark introduced the duo in a 1996 collection of four stories, "My Gal Sunday" (Simon & Schuster, $6.99). She brought them back for "Power Play," a short story that was her contribution to an anthology, edited by Otto Penzler and published in February 1998, "Murder for Revenge," now out of print.
In that story, written sometime in 1997, Henry and Sunday are vacationing in India, and, to avoid the paparazzi, they check into their hotel in disguise, signing the register as Harry and Sandra Potter.
Their hopes for a quiet time, however, are for naught.
Clark writes that, even as Secret Service agents are realizing that the ex-president isn't where he's supposed to be, they get bad news about their incognito charges from a television screen in their office:
'The victims are the wife and daughter of media mogul Winston Andrews; philanthropist Lloyd Cameron and his wife, Audrey, founder and CEO of the Audrey Cosmetics empire. Not much is known about the other two, Harry and Sandra Potter, a retired educator and his wife from Massachusetts.'"
Eventually, of course, Harry Potter and his wife foil the kidnapping, just after the bad guys learn their real identities.
Clark says she gave Henry Britland the Harry Potter alias because "it seemed the most innocuous name I could think of."
She says that, when she gave Henry the Potter name, she hadn't heard of Rowling's young wizard, who first reached British bookstore shelves in mid-1997 and wasn't even mentioned by a U.S. publication until January 1998.
But Clark and Rowling weren't the only ones who found the name Harry Potter artistically useful.
More than a decade before either of their Harrys reached print, the 1986 movie "Troll" in which the evil title character takes over the body of a little girl when her family moves into a San Francisco apartment building featured two Harry Potters.
One was the girl's father, Harry Potter Sr., played by Michael Moriarty, better known for his portrayal of Assistant District Atty. Ben Stone in the "Law & Order" television series in the early 1990s.
The other was Harry Potter Jr., played by Noah Hathaway, who, two years earlier, had appeared as a young warrior named Atreju in "The Neverending Story."
But before you run out to rent "Troll," be advised: Aside from the two Harry Potters, the film, it appears, has little to recommend it.
Definitely not movie magic.