Possible Bug with Chest Crafting System

<reposted from General Chat in case it's a bug>

Ok first off, while it's an obvious money making venture, I LOVE the crafting system. I've spent about $300 on chests in the past few weeks, and don't regret a dime, as I enjoy the fun and excitement, and have got some cool previously unavailable (to me, cos they are old ones) skins, and got a chance to play some champs I wouldn't have purchased outright. That being said, I do have one MAJOR complaint about the way the algorithms work!

When I re-roll on Skins, which essentially costs $5-$7 to do (being 3 skins) and get back one of the effing skins I just re-rolled, that's a bit fekkin lame! Surely you could build into the algorithm that there's ZERO chance of getting one of the same skins back! I mean considering how much money you're making off the system, and the fact that you have full time devs working for you, is that really that hard to do and that much to ask? It's happened to me several times so far, and I think it's just lame!!

If this is a glitch, fair enough, fix it, but if it's not, please considering reworking the way the random rolls work!