Here in the printer’s manuscript, Oliver Cowdery initially wrote “& now behold my Sons”. Shortly afterwards he crossed out this behold because after “my sons” there is another behold. The deletion of the first behold appears to have been virtually immediate since there is no difference in the level of ink flow for the crossout.
One possibility here is that Oliver Cowdery wrote two behold ’s in 𝓟 because there were two behold ’s in 𝓞. One needs to consider the possibility that the repetition of the two behold ’s is actually correct (that is, the original text read “and now behold my sons behold I have somewhat more to desire of you”). Yet it turns out there are no examples in the original Book of Mormon text where behold occurs twice within the same sentence unless the behold ’s occur in different clauses or there is some intervening parenthetical text or a subordinate clause between the behold ’s, as in the following two examples:
For similar examples of multiple behold within the same sentence, see the discussion under Jacob 6:1.
We therefore seem to have some kind of scribal error initially in 𝓟 for Helaman 5:8. The most likely reason for the repetition is that Oliver Cowdery accidentally anticipated the following behold and wrote it too soon, especially since the phrase “and now behold” is very frequent in the text (occurring 113 times in the original text). There is one example of dittography involving behold in 𝓟, namely, in Alma 12:27. In that case, scribe 2 of 𝓟 wrote behold behold; the 1830 typesetter, John Gilbert, interpreted the repeated behold as a simple scribal error, which it probably was (see the discussion under that passage). There Gilbert crossed out the second behold in 𝓟 with pencil.
Thus the odds are that the repeated behold in Helaman 5:8 is a simple scribal error that Oliver Cowdery virtually immediately corrected by crossing out the first behold.
Summary: Accept in Helaman 5:8 Oliver Cowdery’s crossout of the first behold that he originally wrote in 𝓟; here Oliver seems to have anticipated the behold that comes after “my sons”.