Here the angel is speaking to king Benjamin and gives an extended title for Jesus Christ. But in typesetting the 1830 edition, the compositor made a slight change in the phraseology when he accidentally omitted the repeated preposition of in the phrase “the Father of heaven and of earth”. Elsewhere in the Book of Mormon text, the of is always repeated in the specific phrase “the Father of heaven and (of ) earth”:
The second example (Helaman 14:12) is striking in that its phraseology, beginning with the name Jesus Christ, agrees word for word with the original text in Mosiah 3:8: “Jesus Christ / the Son of God / the Father of heaven and of earth / the Creator of all things from the beginning”. In this second example, the speaker is Samuel the Lamanite.
This identity in phraseology was first claimed by John W. Welch on page 22 in Reexploring the Book of Mormon (Salt Lake City and Provo, Utah: Deseret Book and FARMS, 1992), despite the fact that in the current LDS and RLDS texts the identity is not complete since the repeated of is missing from Mosiah 3:8. The critical text will restore the repeated of; and thus the extended title that both king Benjamin and Samuel the Lamanite used to refer to Christ will read precisely the same. For further discussion regarding the repetition of the preposition of in conjoined structures, see conjunctive repetition in volume 3.
Summary: Restore in Mosiah 3:8 the earliest reading with its repeated of in the phrase “the Father of heaven and of earth”; this emendation makes the extended title for Christ agree precisely with the same 21 words in Helaman 14:12.