Yes, mailing lists can be merged together.
- Click on "My Lists."
- View previously uploaded lists are displayed here, or upload a new list.
- Click the button to the left of each list, and a "Merge Lists" button will appear above the table.
- A screen will display the merged addresses pulled from each of the lists.
- Click the "Save" button, and a new list will appear in "My Lists." The original, un-merged lists will also still be available.