Board Thread:Naruto Discussions/@comment-9782468-20140811214915/@comment-23887466-20140811234450

That's not the case, Kakashi didn't copy the Rasengan with Sharingan. He told Naruto that if he was able to mix his Lightning Release with Rasengan, he wouldn't bother himself by creating Chidori and he created Chidori before getting the Sharingan.