Typically, you would need to create a duplicate of a preset when you want to use the same settings file, but a different DITAVAL file. In such a scenario, you can easily create a duplicate preset and use it with a publishing task.
On the FrameMaker Publishing Server dashboard, do one of the following:
Click a preset’s name and in the Publish Preset dialog, click the Duplicate icon.
Select a preset and then select Duplicate Preset from the Add New Preset drop-down.
Open the duplicate preset, edit the required files, and click Save.