Copying an Autoresponder is simple and easy. Once you get to the Autoresponder page (Contacts > Autoresponder).
You will just need to click Action to the right of the Autoresponder you want to Copy. Then choose Copy from the drop down list.
Once you have selected this you will get a pop up screen asking you which series you would like the Campaign copied to and then select when to send this email or choose to change it to Draft so that you can make edits.