Thanks for your message. You can copy test cases within TestRail by using the Copy/Move feature of the TestRail toolbar. Let’s say you want to copy cases from Suite A to Suite B. Just navigate to Suite B and click the Copy/Move icon:
(The Copy/Move icon is the one with two sheets of paper)
You can then select the project/suite and cases you want to copy. You can use the same method to copy entire suites. To copy an entire suite, just create a new empty suite and copy all cases of an existing suite (there’s a Select All link in the copy dialog to make this easier).
I hope this helps!