Quest Item duplicated and is now stuck in inv

Hi Guys,

I just did the Reforging Bench Quest, but i didnt follow the quest path but instantly went to the boss and killed him instead of manually entering the molten vault. He then dropped me the Hammer but i couldnt give it to Oswald. Now after doing the quest, Oswald only took 1 of the 2 hammers and now im stuck with the Hammer of Kamasa in my Inventory. can i somehow delete it out of my inv? This looks like a bug to me.