Copying reports is a very useful function as you can create an exact copy of an existing report, then make changes to the copy. This allows you to maintain the original report. A common situation is copying a report for a previous event, and changing which event you are pulling data from to your current event.
Copying a report
Go to Reports > Reports
Use the 'Tools' dropdown and select "Copy..."
Choose the report to copy (reports in alphabetical order)
Provide a new name for your report