There are two main stories in 1 Nephi and they have certain similarities in common: the story of Nephi building a ship in 1 Nephi 17–18, and the story of retrieving the brass plates back in 1 Nephi 3–5. The stories are both about the same length, and in each case, Nephi succeeds where Laman and Lemuel say it cannot be done. The angel of the Lord or the power of the Lord is manifest in both stories, and in both stories, Nephi mentions Moses in his arguments about how the Lord will deliver them, particularly how the Lord brought Moses and the Israelites out of Egypt just like He brought Lehi’s family out of Jerusalem.
These stories are not identical, but they make a matched pair. We might call them a doublet. We see doublets in the scriptures fairly often, for instance, in the parallels between Hannah giving Samuel to the priest, and John the Baptist being born to Elizabeth and Zacharias. It seems that the authors of the scriptures wanted to have these narrative echoes come to mind so we can recognize the hand of the Lord operating consistently in similar contexts.