The 1849 LDS edition and the 1953 RLDS edition both read nor more, an obvious typo. The probable source for the extra r was the following word more (thus we end up with a rhyming pair, nor more). The 1953 typo, of course, was created independently of the 1849 one. As might be expected, this typo is not found later on in this verse, which reads without variation in the editions as “yea I was harrowed up by the memory of my sins no more” (Alma 36:19).
Summary: Maintain both occurrences of no more in Alma 36:19.