[CLIENT] When I was in champion select it showed me a friend's mastery pages rather than my own

So to provide some context: I was looking at a friend's mastery pages to see how to create mine for a champion he plays. Only when I went in to champion select ~10 minutes later, I clicked the drop down to chose my masteries and his pages were shown rather than mine, both the names and the actual pages had been changed, not my runes though.