It could have been changed at some point. If not, there's no reason the previous parts of the mission should get in the way, but it's been known to happen with NPC's that give out, or are the target of, multiple missions.
You can try going to Berta with all of the meat and such that you need for the stew and the burger, and trade them to her without the mission text. That works in a lot of instances, and if it doesn't, you should get the items back anyway.
I'll check more in to it if there are still issues