You can duplicate a Bill Theme if you want all, or most, of the settings that you customized in an existing theme to be carried over to a new theme.
To do so, go to your Clio Settings panel then click on "Billing" in the Clio Settings column. On the Bill Settings screen, click the "Bill Themes" sub-tab. To copy an existing theme, click the associated "Copy" link.
Once you do, you will see the copied Bill Theme in the list. Next, click on the copy to rename it.
From the Edit Bill Theme screen, click the "Rename" button to update the name.