But Crown, a division of giant publisher Random House which published the McCafferty bestsellers, asserts the plagiarism count to be at least 40.
It issued a statement on Tuesday that 19-year-old Viswanathan's apology to McCafferty was 'deeply troubling and disingenuous.'
Meanwhile, Harvard University said Viswanathan's admission of plagiarism for her book How Opal Mehta Got Kissed, Got Wild, and Got a Life will not affect her academic standing there.
Her publisher Little, Brown, which paid her a $500,000 advance for two books, is also standing by her for now, saying it believes Viswanathan when she says she had unintentionally created passages akin to McCafferty's books.
Little, Brown said it would not recall Opal Mehta from book stores, but a future edition will have the passages rewritten.
However, there seems to be no forgiveness for Viswanathan from McCafferty and her publisher.
McCafferty is said to be anguished by Viswanathan's plagiarism. What upset her particularly, according to reports circulating in New York, is that Viswanathan recently told her hometown newspaper The Star-Ledger, which has over a million readers in New Jersey and New York that 'nothing I read gave me the inspiration' for the Opal Mehta book.
Viswanathan's fun-filled book is the story of Opal Mehta, an ambitious teenager from New Jersey who despite her fine academic record at high school and impressive extracurricular activities is rejected at Harvard. The university's admission dean asks her to return to Harvard after getting a social life, and she sets out to do just that with the help of her unconventional parents.
The second Opal Mehta book, which is to be published next year, deals with her life at Harvard.
McCafferty's books, which have been teen favorites for over five years, follow Jessica, a New Jersey girl who despite her scholastic achievements, has an identity crisis and longs for a romantic life.
Viswanathan, who was born in Chennai and lived in Scotland with her physician parents before migrating to America, told rediff.com last week she had initially not planned to make Opal an Indian. But given many of the funny things she had seen in the Indian community and her observations of the near obsession of Indian parents to send their children to elite universities led her to make the change.
Fox News, which reported publisher Crown's statement, also mentioned reports in The Harvard Crimson that the publisher 'considered this extensive taking from Ms McCafferty's books is nothing less than an act of literary identity theft.'
Fox said, without offering details, that Crown's lawyers were in talks with Little, Brown, a subsidiary of Time Warner.
'We have documented more than 40 passages from Kaavya Viswanathan's recent publication that contain identical language and/or common scene or dialogue structure from Megan McCafferty's first two books,' the statement said.
The first print order for Viswanathan's book, which is already on The New York Times and many regional bestsellers lists, was 100,000 copies. Most new writers would consider a 20,000 print order lucky, and a $25,000 advance gratifying. Crown said McCafferty's two novels, which also deal with teenage anguish and inadequacies, have sold more than 400,000 copies in America, a very impressive sale indeed.