In the original manuscript, spacing between extant fragments shows that in all probability Oliver Cowdery initially wrote “to repent of all the many murders which we have committed”. Later he probably inserted our sins & supralinearly at the end of the line in 𝓞:
None of the supralinearly insertion is actually extant in 𝓞, but it was probably there when Oliver copied the text from 𝓞 into 𝓟. Interestingly, in that copying process, Oliver accidentally omitted the and that would have been written as an ampersand at the end of the supralinear insertion in 𝓞. Scribe 2 of 𝓟 later supplied the ampersand when he proofed 𝓟 against 𝓞.
Two similar versions of this conjunctive expression are found in the preceding text:
These references to sins and murders are found six and three lines earlier in 𝓞, so it is theoretically possible that in verse 11 Oliver added the extra our sins, either accidentally or intentionally, as he copied the text from 𝓞 into 𝓟. If so, this would imply that scribe 2’s insertion of the ampersand was based on editing rather than on correcting to 𝓞. Nonetheless, there is no evidence elsewhere in the text for such interference from a specific expression unless that expression is common or is found within a line, rarely two lines, in the manuscript. Ultimately, the safest solution here is to assume that the original text in verse 11 read “to repent of all our many sins and murders”, the corrected reading in 𝓟 (and the earliest extant full text for Alma 24:11).
Summary: Maintain in Alma 24:11 the conjunctive expression “of all our sins and the many murders which we have committed”, the corrected reading in 𝓟.