The final duel between Ewan McGregor's Obi-Wan Kenobi and Hayden Christensen's Anakin Skywalker in Star Wars: Episode III – Revenge of the Sith was almost completely different – and the stars preferred the other version. The future may always be in motion in Star Wars, but viewers watched the entire prequel trilogy knowing where the story would end. Anakin Skywalker was always destined to fall to the dark side, and to be defeated in a fateful duel with his former master, Obi-Wan Kenobi. As dramatic as that final battle may have been, though, aspects of it have been much criticized by viewers – including an odd line of dialogue in which Obi-Wan claimed victory purely because he had the high ground.

https://screenrant.com/revenge-sith-obi-wan-anakin-alternate-duel-mustafar/