You will need to create a new template via the Advanced Report Creator with a different name.
These can then be added through Posting Maintenance and can be amended per Case Type:
From the Main Menu go to Posting Maintenance.
Select the BILL PRINTS tab.
In the bottom there should be a grid called Documents to Produce.
There should be an item called Bill Print this is where the bills link to and the type.
Select UPDATE.
Select the pad icon and edit the document name to the new document you have created.
Select the SAVE option.