Here Oliver Cowdery initially wrote “the wickedness and abominations of his people” in 𝓟. Then almost immediately he supralinearly added the definite article the before abominations (the level of ink flow is unchanged). Elsewhere, the text has ten occurrences of “the wickedness and abomination(s)” (that is, without the repeated definite article). In only one other place is there evidence for the reading “the wickedness and the abomination(s)”:
It appears that in Helaman 13:16 the 1830 edition accidentally omitted the the before abominations (for further discussion, see the analysis of that passage). The overall tendency in the history of the text has been to accidentally omit the repeated determiner. The example here in 𝓟 for Mosiah 3:7 provides one more example of this tendency. For a complete analysis of the repetition of determiners in conjunctive structures, see conjunctive repetition in volume 3.
We get more variability with respect to conjuncts of wickedness and abomination(s) when the determiner is a possessive pronoun. We have the following statistics based on the earliest extant readings:
their wickedness and abomination(s) 12 times
their wickedness and their abomination(s) 8 times
your wickedness and abomination(s) 3 times
your wickedness and your abomination(s) 0 times
his wickedness and abomination(s) 0 times
his wickedness and his abomination(s) 1 time
This variability suggests that we should rely on the earliest textual sources in determining whether the definite article the should be repeated in “the wickedness and (the) abomination(s)”. Since the supralinear correction appears to be virtually immediate in Mosiah 3:7, the critical text will accept the reading with the repeated the.
Summary: Retain in Mosiah 3:7 Oliver Cowdery’s corrected reading in 𝓟 (“the wickedness and the abominations of his people”); the nearly immediate correction appears to be based on the reading of the original manuscript, no longer extant for the book of Mosiah.