Is it possible to have more than one administrator with each having their own login?
Yes, this is possible.
From our Business accounts you can create an organization. All members of an organization can administrate PollUnits created within this organization. In out Enterprise account you can manage multiple organizations.
In the context menu of each PollUnit you can move a private PollUnit to one of your organizations.
You find more information here: https://pollunit.com/en/tutorials/organization