Multiple superuser roles?

Yep! Within the context of an already-created Vertica database, any user with the PSEUDOSUPERUSER role is treated as the superuser for purposes of permissions. That is to say, anywhere in Vertica where being the superuser allows you to bypass a privilege check or do something elevated, so does PSEUDOSUPERUSER.

The main difference between the real superuser and "pseudosuperusers" is that superuser access cannot be revoked for the superuser created during database creation.

More info in the docs.