1. Settings > Users & Companies > Groups > Click on "User types / Internal User"
2. Remove the data in "Application" field and save it
3. Click Action button at the top and click "Duplicate"
4. Group will be duplicated with all details (access rights, record rules, users, menus, inherited) of existing group and name will be automatically display as "Internal User (copy)"
5. Click "Edit" button and set the application field as "User Type" in the duplicated record
6. Again navigate to the group from which you duplicated and set the application field as "User Type"
7. Now while creating new user, the option "Internal User (copy)" will be added in the "User Type" field

Note: When you try to duplicate the group without removing the data of application field, it will raise a warning error as "User cannot have more than one user type"