"Duplicate the Selected List" feature
a new list within the Selected Group by simply duplicating the Selected List. You also have the
option of screening out duplicate addresses.
The Selected List remains completely intact.
Why? Lists are frequently duplicated to preserve the original list at a specific point in time. Customers typically use this feature when requesting RSVP confirmation regarding attendance, etc. They duplicate a list and then use the toggle function to toggle the RSVPs. They then use the "Split the Selected List" feature to identified those that have and have not RSVP'd. Those that have not are then sent a second follow up. Etc.