The 1830 typesetter added the repeated of here, thus producing a more repetitive conjoined structure for the phrase referring to “the Father of heaven and earth”. Such a structure, with the repeated of, occurs in five other places in the original text:
For the example in Mosiah 3:8, the second of was accidentally deleted by the 1830 typesetter, thus producing for that example the reading without the repeated of in all the printed editions: “the Father of heaven and earth” (see the discussion under Mosiah 3:8). One could argue from the error in Mosiah 3:8 that in Alma 11:39 a similar repeated of was accidentally omitted in the early transmission of the text but was then restored by the 1830 typesetter (probably unintentionally). We should also note that here in Alma 11:39 the reference to the Father reads “the very Eternal Father”, not simply “the Father”; Mosiah 15:4 also refers to “the very Eternal Father”, and it has the of before earth.
The Book of Mormon does have a conjunctive expression involving heaven and earth without any repeated of: namely, “by the help of the all-powerful Creator of heaven and earth” (Jacob 2:5). Similar usage is found in the King James Bible:
More generally in the King James Bible, the preposition of is sometimes repeated in conjuncts of heaven(s) and earth, as in Genesis 2:4: “these are the generations of the heavens and of the earth when they were created”. A similar example is found in the Book of Mormon:
Such variation in usage, in both the King James Bible and the Book of Mormon, argues that the earliest reading for Alma 11:39 (namely, without the repeated of ) is possible. The critical text will therefore restore that reading.
Summary: Remove the intrusive of in the conjoined structure in Alma 11:39, thus restoring an appropriate conjunctive relationship for the Book of Mormon text: “the very Eternal Father of heaven and earth and all things which in them is”.