ORA-16621

Error: ORA-16621: host and SID names for create site must be unique

Causa: This status is returned when an attempt is made to add a site whose host and SID names match those of an existing site.

Acción: Verify that you have specified a unique host and SID name pair for the new site you wish to add. This can be done by checking that there are no sites with the same host and SID names.