Let's see what the downvote button's tooltip has to say about this:
This question does not show any research effort; it is unclear or not useful
If you ask a duplicate question without mentioning things you've searched for and looked at, people very well might downvote you. You should at least look through the questions suggested by the new-question title box's search feature. If a duplicate question appears in the sidebar under "Related" after you post your question, you're going to get closed in a hurry and probably downvoted once or twice too.
I suggest using Google to search for several ideas/terms related to your question. (Bonus points for using the advanced features - putting
site:superuser.com in the query makes Google search only Super User.) If you think your question is widely-applicable enough that people have probably thought of it before (e.g. "Aaaaah! My drive shows up as RAW and I can't access anything!"), you'd better do some serious searching here first. Be aware that Stack Exchange search - the box in the upper-right - is not the best, and Google does a lot better.
A well-written duplicate question that somehow didn't find the original in reasonable searching efforts is not a terrible thing. Conversely, if you ask a duplicate and ask it badly (unclear or poorly formatted), prepare for downvotes. I personally downvote duplicates very rarely.