I think we should have more information in the related questions sidebar item. For example, we could have an indication of whether a question has an accepted answer, how many votes it has, and how many answers are present. This helps you pick the best question when identifying a possible duplicate, instead of just reflexively clicking on the first link.
An example of what it could look like (taken from something else I was working on). Looks pretty ugly, but I'm no UI designer:
Links in green are questions with accepted answers (a nicer alternative would be a low contrast green background, or a checkmark), and a number after the title indicates how many answers the question has.