As someone who first heard Bob Marley's music in 1973 and followed him through the course of his musical career until he passed in 1981, I really don't see the similarities in "Stir it Up" and TTTYAATW.
But Bono always loved and respected Brother Bob's music and message so undoubtedly there are Marley influences in Bono's lyrics.
Bono has sung bits of "One Love" "Three Little Birds" "Exodus" "Get Up, Stand Up" and "Redemption Song" in various U2 concerts over the years, so the musics of U2 and Marley are DEFINITELY LINKED.
Thanks though for bringing up the idea of the musics of Bob and Bono as ONE at Heart.
Their main influence come from the same source (God).
ONE LOVE, ONE HEART - LET'S GET TOGETHER AND FEEL ALRIGHT....