The first time Orson Pratt and Joseph F. Smith (JFS) visited the Hill Cumorah near Palmyra, New York, was in September 1878. Orson was 68 years old and had testified about the Hill Cumorah many times but had never had the opportunity to see the hill or visit historic sites in the area.
At the time, Orson was Church Historian. President John Taylor had sent him and JFS on a fact-finding mission to sites of early Church history. An overview of their trip is here:
The two men were traveling together from Utah to New York City. They sent reports of their trip to the Deseret News that were published as installments. The report of their visit to Cumorah is here:
In the following installment, they discuss their interview with David Whitmer on 7–8 September 1878. This is the interview in which David Whitmer describes the angel who showed them the plates, surrounded by glorious light. Later, he describes the divine messenger, a heavy-set old man in a brown wool suit, who was taking the abridged plates to Palmyra. These were unmistakably different individuals.
David explains it was this same messenger who showed plates to his mother, Mary Whitmer. (She said he called himself "Brother Nephi.") These were the plates Joseph translated in Fayette, which means they were the original plates of Nephi (the so-called "small plates."
Notice that David saw both the angel and the messenger and never said or implied they were the same person.*
Orson Pratt died on October 3, 1881 at the age of 70 (he was born September 19, 1811, in Hartford, New York.) He was the last member of the original Quorum of the Twelve Apostles to die.
The next year, The Contributor posthumously published an article written by Orson about the Hill Cumorah. You can read it here:
This is a reprint of an article Orson published in the Millennial Star in 1866.
In this article, Orson explains there were two departments in the hill of Cumorah.
The Hill Cumorah is situated in western New York between the villages of Palmyra and Canandaigua about four miles from the former. It is celebrated as the ancient depository of the sacred gold plates from which the Book of Mormon was translated. Cumorah was the name by which the hill was designated in the days of the Prophet Moroni who deposited the plates about four hundred and twenty years after the birth of Christ.
The prophet Mormon, the father of Moroni, had been entrusted with all the sacred records of his forefathers engraved on metallic plates. New plates were made by Mormon on which he wrote, from the more ancient books, an abridged history of the nation, incorporating therewith many revelations, prophecies, the Gospel, &c.
These new plates were given to Moroni to finish the history. And all the ancient plates Mormon deposited in Cumorah, about three hundred and eighty-four years after Christ. When Moroni, about thirty-six years after, made the deposit of the book entrusted book entrusted to him, he was, without doubt inspired to select a department of the hill separate from the great sacred depository of the numerous volumes hid up by his father.
The particular place in the hill, where Moroni secreted the book, was revealed, by the angel, to the Prophet Joseph Smith, to whom the volume was delivered in September, A.D. 1827. But the grand repository of all the numerous records of the ancient nations of the western continent, was located in another department of the hill, and its contents under the charge of holy angels, until the day should come for them to be transferred to the sacred temple of Zion.
*Even though David said the published Testimony of the Three Witnesses "is strictly and absolutely true," we have some current LDS scholars who, because of M2C, teach that the angel and the old man were the same person: Moroni.
Yes, they are teaching their students (and the world) that resurrected beings have the ability to shape shift.
Accordingly, I offer the revised Testimony of the Three Witnesses: