Complex sentence: This was the only heavyweight unification fight since Wladimir Klitschko and Sultan Ibragimov fought back in 2008, when Wladimir Klitschko beat Ibragimov and added his WBO title to his IBF title.
Split into simpler sentences: This was the only heavyweight unification fight since Wladimir Klitschko and Sultan Ibragimov fought back in 2008. It was then when Wladimir Klitschko beat Ibragimov and added his WBO title to his IBF title.