Hmm, the title of entry seems a bit duplicated -- but hey, this posting is all about how to replicate an existing survey, so perhaps it is appropriate.
So, you have an existing survey, and you want to create a new survey that is very similar to your existing one, but of course, you don't want to retype 100 questions!
No problems! You can export an existing survey structure (note structure -- not data) to CSV format. Then, create a new survey and just import your CSV file again. Voila, a duplicated survey. Next, you can proceed to edit the new survey to customize it.