The 1840 edition added a repeated in before “the wilderness round about”, thus creating a typical Hebraistic coordinate structure (“in X and in Y”). The original manuscript is not extant here, and the spacing between extant fragments is quite long, so it is difficult to determine if the repeated in was in the original manuscript.
The 1840 addition of in could be due to Joseph Smith’s editing, although such a change is not at all typical of his editing. If anything, we expect the text to accidentally drop out repeated prepositions rather than add them. On the other hand, we know that Joseph used the original manuscript to restore in the 1840 edition a handful of phrases that had been accidentally deleted in preparing the printer’s manuscript. But the insertion of this single short preposition in is uncharacteristic of Joseph’s restoration of whole phrases in the 1840 edition. The most probable reason for this 1840 change is that it simply represents a typo on the part of the typesetter for that edition. Even if the repeated in was in the original manuscript, its possible restoration in the 1840 edition would have been simply fortuitous. For further discussion of prepositional repetition, see under conjunctive repetition in volume 3.
Elsewhere in the Book of Mormon text there are numerous examples of repeated in ’s. There is, however, only one other case where wilderness is conjoined within a prepositional phrase headed by in:
We note here that the in is repeated, but only before “your wilderness”, not before “your secret places”. This irregularity may actually be due to the fact that earlier in English the word closet referred to a secret or private place—as in the King James text for Matthew 6:6 (“when thou prayest / enter into thy closet”), also quoted this way in 3 Nephi 13:6. In other words, one could argue that the in is not repeated before “your secret places” in Alma 34:26 because this phrase is closely associated with “your closets”.
If we consider the possible repetition of other prepositions with a following conjoined wilderness, we get two more examples:
The first example shows a repetition of into, but the second one does not repeat the out of, so it appears that a conjoined wilderness does not necessarily require a repetition of the preposition. (Incidentally, the first example also shows another case where the conjunct “secret places” avoids repetition of the preposition.) Thus it is probably best to retain the earliest attested reading in Alma 22:34, the one without the repeated preposition (“and the wilderness round about”).
Summary: Retain in Alma 22:34 the earliest attested reading without the repeated preposition in (“and the wilderness round about”).