Rito pls

So for the past 2-ish weeks I've been grinding out the norms to get some key fragments. After 2 weeks, I finally got 3 key fragments and I was so happy; I opened my chest and I get Yasuo. The champion I played the match prior. Is there anything you guys might implement so that players won't get champions or skins they already own? I feel kinda cheated, then again, it's an RNG based system, so I don't think there's much you can do. Thanks for your time.