I have multiple copies of quite a few items, mostly rewards for weeklies or things like that. It serves absolutely not purpose and cannot be smelted into craftable material either... I don't think Killing Floor 2 has a limit for the amount of items you can have in your inventory though? So it's not even that big of a deal. It's just worthless really.
I guess that's an oversight by Tripwire. And I also guess we're far from being alone with that "issue".