From what I know, Yuki Yubari was intended to be the dominant Yubari sister, and had a whole subplot to herself, Yuki's revenge. In fact GoGo didn't originally have any lines, all the ones she has know belong to two characters that were "written out", Yuki and Mr Barrel (who was going to be a more indepth Johhny Mo type character the Bride convinces to leave Oren). However, the actress Tarantino wanted for the part was unavailable, Kou something, as was Mr Barrel. Thus, they were written out and GoGo benefited, she still would have had an A+ battle, but just no lines. In fact from what I hear Tarantino was so determined to retain Yuki's Revenge he tried many things, like suggesting GoGo and Yuki could be twins and thus have Chiaki Kuriyama play both. However I think in the end it was realised the movie was already quite long, and the idea dropped...... for now........