Here in the original manuscript, Oliver Cowdery wrote more im at the end of a line, then crossed it out. It looks like he started to write “they became more impenitent” but then corrected the text to read “they became more hardened and impenitent”. The phrase “more hardened and impenitent” is not extant, but it fits in the lacuna precisely. One could interpret the initial more im as meaning that the original text here read “they became more hardened and more impenitent” but that the repeated more was accidentally lost when Oliver corrected his initial miswriting in 𝓞. It is at least clear that there is no room for an extra more in the lacuna except by supralinear insertion.
Another factor to consider here is that more occurs once more in this sentence: “and more wild wicked and ferocious”. Yet in this second conjunctive phrase, the more is not repeated; that is, it does not read “and more wild / more wicked / and more ferocious” (or some variant of that). Thus there is nothing wrong with “more hardened and impenitent”, the earliest extant reading (the reading in 𝓟). The critical text will therefore retain the reading without more before impenitent.
Summary: Maintain in Alma 47:36 the two occurrences of more in “they became more hardened and impenitent and more wild wicked and ferocious”; based on manuscript evidence, there is no firm support for any additional occurrences of more in this clause.