Snowdown Chests

Basically I decided to put quite a bit of money (roughly $60 USD) into Hextech Crafting for the Snowdown event in order to get as many Poro King Boxes as possible, since they unlock full skin permanents. I have gotten three so far, but every single one has contained a skin that I already own. Normally that wouldn't be much of a big deal, since I get orange essence for disenchanting them, but with the number of other boxes I have opened to accumulate 3 Poro King Boxes, it makes the money invested into getting them seem a bit wasted. I was wondering if there would be a way to somehow prevent this from happening in the future, not even for my own sake, but for anyone else who might experience this same situation. It just makes you feel really bad about the whole system. It's fun to randomly roll through boxes to see what you get, but when you're expecting at least one permanent skin and get nothing 3 times, it seems a little unfair when you consider the investment behind trying to get as many Poro King Boxes as possible.