This article explains how to duplicate an assessment. This feature is only available to users with administrative permissions.
How to Access Assessments
Select "Courses" from the admin menu.
Select "Add/Edit course assessments", then click the Next button.
How to Duplicate an Assessment
Click the "Duplicate" link next to the assessment that you would like to duplicate. See image below.
You'll then be promoted to OK the process. You're done.