Mosiah 10 repeats a large number of elements from Mosiah 9, mostly in the same order and often in nearly the same language. This was discovered by Ganesh Cherian, who discusses it on YouTube
here,
here, and
here.
This is presented, particularly in the last video, as evidence against the authenticity of the Book of Mormon. The idea is that Joseph Smith had memorized "Mad Libs" style templates that he would use in dictating the text, and that in this case he used the same template twice in a row.
Of course, if only Mosiah 10 had repeated the elements in reverse order rather than in the same order as Mosiah 9, it would be an extended chiasmus, one of the apologists' favorite evidences for the authenticity of the Book of Mormon. So I don't see why the repetition Cherian has found couldn't also be a form of literary parallelism used by the Nephites. In my mind, the fact the repeated series of elements comes immediately after the original makes the parallelism theory more plausible; if the two parallel series were in entirely different parts of the book, that would be more consistent with the Mad Libs theory.
Anyway, however you interpret them, the parallels are indisputably there in the text. The purpose of this post is to document them in text form for ease of reference, since it appears Cherian's own work is all in video format. (I also identify the specific parallels somewhat differently from Cherian, though he deserves 100% of the credit for noticing them.)
[9:7] And he also commanded that his people should depart out of the land, and (A) I and my people went into the land that we might possess it.
[9:8] And we began to build buildings, and to repair the walls of the city, yea, even the walls of the city of Lehi-Nephi, and the city of Shilom.
[9:9] And we began to (B) till the ground, yea, even with (C) all manner of seeds, with seeds of corn, and of wheat, and of barley, and with neas, and with sheum, and with seeds of (D) all manner of fruits; and (E) we did begin to multiply and prosper in the land.
[9:10] Now it was the cunning and the craftiness of king Laman, to bring my people into bondage, that he yielded up the land that we might possess it.
[9:11] Therefore it came to pass, that after we had dwelt in the land for the space of twelve years that king Laman began to grow uneasy, lest by any means my people should wax strong in the land, and that they could not overpower them and bring them into bondage.
[9:12] Now they were a lazy and an idolatrous people; therefore they were desirous to bring us into bondage, that they might glut themselves with the labors of our hands; yea, that they might feast themselves upon the flocks of our fields.
[9:13] Therefore (F) it came to pass that king Laman (G) began to stir up his people that they should contend with my people; therefore there (H) began to be wars and contentions in the land.
[9:14] For, in the thirteenth year of my reign in the land of Nephi, away (I) on the south of the land of Shilom, when my people were watering and feeding their flocks, and tilling their lands, a numerous host of Lamanites (J) came upon them and began to slay them, and to take off their flocks, and the corn of their fields.
[9:15] Yea, and it came to pass that they fled, all that were not overtaken, even into the city of Nephi, and did call upon me for protection.
[9:16] And it came to pass that I did (K) arm them with bows, (L) and with arrows, (M) with swords, (N) and with cimeters, and with clubs, (O) and with slings, and with all manner of weapons which we could invent, and I and my people did (P1) go forth against the Lamanites to battle.
[9:17] Yea, (Q) in the strength of the Lord did we (P2) go forth to battle against the Lamanites; for I and my people did cry mightily to the Lord that he would deliver us out of the hands of our enemies, for we were awakened to a remembrance of the deliverance of our fathers.
[9:18] And God did hear our cries and did answer our prayers; and we did go forth in his might; yea, we did (P3) go forth against the Lamanites, and in one day and a night we did slay three thousand and forty-three; we did slay them even until we had driven them out of our land. [. . .]
[9:19] And I, myself, with mine own hands, did help to bury their dead. And behold, to our great sorrow and lamentation, two hundred and seventy-nine of our brethren were slain.
[10:1] And it came to pass that we again began to establish the kingdom and (A′) we again began to possess the land in peace. And I caused that there should be weapons of war made of every kind, that thereby I might have weapons for my people against the time the Lamanites should come up again to war against my people.
[10:2] And I set guards round about the land, that the Lamanites might not come upon us again unawares and destroy us; and thus I did guard my people and my flocks, and keep them from falling into the hands of our enemies.
[10:3] And it came to pass that we did inherit the land of our fathers for many years, yea, for the space of twenty and two years.
[10:4] And I did cause that the men should (B′) till the ground, and raise (C′) all manner of grain and (D′) all manner of fruit of every kind.
[10:5] And I did cause that the women should spin, and toil, and work, and work all manner of fine linen, yea, and cloth of every kind, that we might clothe our nakedness; and thus (E′) we did prosper in the land—thus we did have continual peace in the land for the space of twenty and two years.
[10:6] And (F′) it came to pass that king Laman died, and his son began to reign in his stead. And he (G′) began to stir his people up in rebellion against my people; therefore they (H′) began to prepare for war, and to come up to battle against my people.
[10:7] But I had sent my spies out round about the land of Shemlon, that I might discover their preparations, that I might guard against them, that they might not (J′) come upon my people and destroy them.
[10:8] And it came to pass that they came up (I′) upon the north of the land of Shilom, with their numerous hosts, men (K′) armed with bows, (L′) and with arrows, (M′) and with swords, (N′) and with cimeters, and with stones, (O′) and with slings; and they had their heads shaved that they were naked; and they were girded with a leathern girdle about their loins.
[10:9] And it came to pass that I caused that the women and children of my people should be hid in the wilderness; and I also caused that all my old men that could bear arms, and also all my young men that were able to bear arms, should gather themselves together to (P1′) go to battle against the Lamanites; and I did place them in their ranks, every man according to his age.
[10:10] And it came to pass that we did (P2′) go up to battle against the Lamanites; and I, even I, in my old age, did (P3′) go up to battle against the Lamanites. And it came to pass that we did go up (Q′) in the strength of the Lord to battle.
That's a series of 17 elements repeated in precisely the same order, with two additional elements (I and Q) only slightly out of order. The chance that this is a coincidence is, I think, negligible. And, as I have said, I think the theory that this is a Nephite literary form is more plausible than the Mad Libs theory. I think having to repeat so many elements in the same order, while at the same time moving the story forward rather than just repeating it, would have made the dictation harder for Smith, not easier. And the fact that the repetition comes immediately after the original makes this look more like a single coherent structure than like a case of self-plagiarism.
This is unlikely to be a one-off. I predict that other long repeated series can be found elsewhere in the book -- and that, as here, the repeated series will come immediately after the original. (If once can be found that is not immediately after the original, that would lend more credence to the Mad Libs theory.)