First, here is what the [documentation](https://judaism.stackexchange.com/help/privileges/vote-down) says about downvotes:

> When should I vote down?

> Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.

What does that mean with respect to duplicate questions?  Each user will evaluate this a little differently, but here are some considerations I apply when voting:

- Is the duplicate so close that it would have popped up in the first few entries on the "suggested duplicates" list you get when asking a question?  This can suggest a lack of effort.

- Is the duplicate phrased differently enough that you would have had to know there was a dupe, or do an exhaustive search, to find out before asking?  This can act as a useful signpost for people coming from search engines; people may ask the same question in many different ways.

- Is the new question asked really well while the older one is not?  This could be a candidate for a merge, bringing a well-asked, findable question together with the existing answers.

- Does the question indicate somehow that the author did try to search first?  Not everybody is skilled with searching and Stack Exchange search can be a little iffy sometimes.

- Does the question acknowledge the other question and explain why the author thinks this question is different?  (Even if he's not *right* about that, did he try?)