Can I have more that one administrator?

yes create a new role: administer -> access control -> add role
name it whatever you want, for this example ill use admin.

then assign this role (admin) the necessary permissions after creation.
then visit the users profile you want to make an admin, and issue them this role (admin)

Yes, just create a new role, and give it all permissions. Then assign that role to the user you want to have admin access.

Be careful of course, because if you give full access, they can take over the first user (change password) and control the site.

The first user still have some special roles (needed for module maintenance and when updating).

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