Well, this happens to me more often when i try to use skip button after game while i'm leveling up. I'n the following pic u will see that i unlocked " Splitter " which is a starter wep that already given and can't be unlocked. It's not only splitter, it happens with all starter weps in general.
Happens to me all the time. It could be fixed, but nothing really messing the game up. There are more important problems at hand for KChamp.