https://www.starwars.com/news/iain-mccaig-the-phantom-menace
“For a time, the older Jedi was named Obi-Wan and the younger Jedi was named Qui-Gon. It was very poignant that at the end, as Obi-Wan dies and Qui-Gon defeats Darth Maul and stays with his Master as he passes away, he not only takes on his Master’s quest, but he takes on his name. Qui-Gon becomes Obi-Wan. That’s why when you see Alec Guinness in A New Hope, he puts his hood down and goes, ‘Obi-Wan? Now that’s a name I’ve not heard….’ Because he’s not Obi-Wan, he’s Qui-Gon. And right at the end, George changed it.”