やはり --> "I knew it", "as I thought" Example: "As I thought it was that way." --> やはりそうでしたか かも知れない means "may" and indicates uncertainty. Example: "Mr. Smith may have gone to the cafeteria." --> スミスさんは食堂に行ったかもしれません。

Yahari is like "I knew it" or something. and Kamoshirenai is like a "possibly" at the end of a sentence. It might not be so but it might also be so. It's sometimes shortened in colloquial speech as "kamo". Yahari seems to change exact meaning depending on the context. https://www.japanesewithanime.com/2017/01/yahari-yappari-meaning.html https://nihongoshark.com/kamoshirenai/