[Gameplay] Someone Else's Item Pages Load in for Me

With the new client, we aren't allowed to change item pages but they still exist in the game. I have my item pages (when I used the old client) set for particular champions, and as of recently the only pages I have are for . I remember only having them for her because I never used the pages I made for , , and so I deleted them.

A friend of mine used my laptop to play League, and they have item pages set up for , , , and more, but their pages are set to just any champion rather than those particular champions. When playing champions other than Nami, I get his pages on my account?

I have no idea how to fix it, I have uninstalled and reinstalled the client and even used the Hextech repair tool, but no luck. Nobody else I have talked to seems to have this issue, so I am very confused as to how it happens to me.