There are a number of reasons why you would choose to create a copy of a Survey. You may want to create a survey with a new question and description but keep everything else the same as an existing one. Also Surveys cannot be edited, once you have created a Survey the only way to change it is to create and edit a copy. Subsequently, you would then need to disable the previous one and enable and deploy the copy.
You can copy a single existing Survey by selecting it from the Surveys table and clicking the Clone Selection button. This displays the New Survey page pre-filled with all the details from the selected Survey. When doing this you must change the name of the Survey so it doesn't clash with the previous one. You then modify the rest of the parameters as needed and click Save to save the copy.