Matthew Roper argues that there is not convincing evidence of two Spaulding manuscripts.
Matthew Roper, "The Mythical 'Manuscript Found,'" Review of Books on the Book of Mormon 1989–2011 17, no. 2 (2005): 21-22
“A considerable body of evidence exists,” according to The Spalding Enigma, “indicating that Solomon Spalding wrote a second novel entitled A Manuscript Found, which disappeared prior to 1833” (p. 32). Unfortunately for their position, much of that evidence comes from very late testimony solicited long after the fact, in which “witnesses” recalled, with ever-increasing detail, what Spalding had reportedly done or said through the years. Cowdrey, Davis, and Vanick insist that early evidence for that claim can be found in the statements collected by Hurlbut in 1833. Out of eight statements about Spalding collected by Hurlbut between August and September 1833, however, six (John Spalding, Martha Spalding, Henry Lake, Oliver Smith, Nahum Howard, and Artemus Cunningham) mention only one work. Two former neighbors (John Miller and Aaron Wright) indicate that Spalding had several other papers or writings in addition to his story on ancient America. Since these statements were solicited and obtained by Hurlbut before he retrieved “Manuscript Story” from the trunk of Spalding’s widow, they prove, says The Spalding Enigma, that Spalding wrote a second story that was a revision of his earlier tale “Manuscript Story.” This supposed second version, which was called “Manuscript Found” (p. 79), was allegedly closer to the Book of Mormon. In a statement made in September 1833, John Miller said that Spalding “had written two or three books or pamphlets on different subjects; but that which more particularly drew my attention, was one which he called the ‘Manuscript Found.’” It “purported to be the history of the first settlement of America, before [being] discovered by Columbus.”65 Did any of these other books or pamphlets bear any relation to the Book of Mormon? Miller’s statement gives no indication that they did. In fact, while Miller mentions several “books or pamphlets on different subjects,” he seems to draw a distinction in his statement between “Manuscript Found” and Spalding’s other writings. Howe claimed that Mrs. Spalding told Hurlbut that her husband “had a great variety of manuscripts” but said nothing about their content. In a statement made in 1880, Spalding’s daughter Matilda Spalding McKinstry also referred to “little stories” her father would read to her as a child, one of which she says was called “‘The Frogs of Wyndham,’” in addition to “sermons and other papers.” These might have been what Miller meant by “books or pamphlets on different subjects.” In contrast to these other papers, however, the manuscript that Miller described and that interested him was the one that dealt with an ancient settlement of America long before its discovery by Columbus.