You can have several ZPhoneLists for your ZTerm application.
Just duplicate an existing ZPhoneList (select it and use the Finder’s “Duplicate” command) and change its name. Then, when you double-click on it, Zterm will open and you can change anything which you wish to change in the new list—including adding or deleting phone numbers or changing settings—and it will be maintained as a separate list from the original list from which it was created.
You can create as many different ZPhoneLists as you might find useful. You can choose any of these ZPhoneLists to be the active List simply by double-clicking on it; it will launch ZTerm automatically, and the list on which you double-clicked will be the one showing in the “PhoneList” menu!