Here scribe 2 of 𝓟 initially wrote “by own father Alma”; then virtually immediately he inserted the my, giving “by my own father Alma”. Oliver Cowdery, somewhat later (probably while proofing the printer’s manuscript against the original manuscript) deleted the own. This change is consistent with other usage in the text since only once is own used to modify nouns referring to close family members (such as father, mother, brother, sister, son, and daughter), yet this single occurrence is in a King James biblical quotation:
There is further evidence that the scribes occasionally added own:
In all of these cases, the scribe was Oliver Cowdery; in each example, there are nearby occurrences of own that led Oliver to momentarily insert an extra own. Similarly, in Alma 5:3, there is a preceding own that seems to have prompted scribe 2 of 𝓟 to accidentally add own (thus creating “according to his own record saying : I Alma having been consecrated by my own father Alma”). Oliver’s decision here in Alma 5:3 to remove the extra own was undoubtedly correct and appears to have been the result of comparing 𝓟 against 𝓞.
Summary: Accept in Alma 5:3 Oliver Cowdery’s deletion of own in 𝓟 since such usage is not found elsewhere in the Book of Mormon text proper; moreover, there is a nearby preceding own that seems to have been the source for the intrusive own.