Fallout New Vegas "?": What happens if Benny died at the Fort and I still need the platinum chip?

Throughout the game I choose to side with the NCR the whole time and therefore became vilified with The Fort and hated by the Legion. In one of my quests (trying to get the Great Khans to not ally with The Legion) I had to prove that the Legion makes allies slaves so I snuck into The Fort with lots of stealth boys and Caeser's personal book, while I was there I saw Benny tied up and felt bad so I set him free (he died a mere 2 seconds later by all the guards) but i was still un-noticed. Now when I'm trying to get the platinum chip it says "get from Benny at the Fort" but he didn't have it on him and I'm not sure how to progress through the main storyline...