I've seen at least 2 different Misc. Quests having bugged issues related to the acquisition of the quest item.
Having the quest item before the quest seems to be the issue, I'm guessing if there's code to check if the item already exists in inventory it's not working.

If you've got a quest that you're getting this bug for, post it here so it's more visible.

I really wish the Bethesda forum mods and the devs would improve their bug reporting and resolution methods. Any computer science prof will tell you that you're not done just because you've released the software.
It's a it's a simple matter of better management and would go to great lengths to improve Bethesda's reputation in respect to bugs.