I realize that one of the major goals of this site is to help others learn and understand mathematics, and in fact it is one of my favorite parts of math.SE. As such, I don't mind a bit when I see a user who hardly ever answers but asks lots of questions as long as they are insightful or show a lot of effort on their part. But there are some users who have given almost no answers and ask lots of questions that seem like homework, are asked in the imperative, and show little or no work on their part. Also, this trend in their behavior spans long periods of time and nothing deep about any of the answers they get seems to stick when they ask their next question. My main question is what to do about such users. I realize that given the way math.SE is set up they are bound to pop up, but should we do something to try to discourage this, or simply ignore them?
A more specific question is about what counts as a duplicate. I have noticed one user who I think fits the pattern I described above who also has a habit of creating entirely new questions when they don't understand a small part of an answer to the last question they asked, or when they want to know about a slightly different case/approach. What is the proper course of action here? Do these kinds of questions qualify as "exact duplicates" and warrant closure? I have tried urging this user not to ask these as separate questions but rather edit their old post/comment on answers they don't understand, but without success.
I have avoided giving specific examples here because I don't want this to degenerate into a name-calling fest. If this question seems inappropriate or rude, please inform me and I will delete it if several people object to it.