Override default SERVICE_NAME in init.ora I'd like to define several service names for my instance in such a way that users should not know the actual instance name. This is what I have done in my init.ora:

db_domain='company.com'
db_name='tdbket'
instance_name='tdbket'
service_names=tedab+ket.company.com, tedab.company.com, ket.company.com


By definition, the default value DB_UNIQUE_NAME.DB_DOMAIN of the service_names attribute should be overridden.

Though, the Listener still lists this default value:

Dienst "ket.company.com" hat 1 Instanzen.
  Instanz "tdbket", Status READY, hat 6 Handler für diesen Dienst...
Dienst "tdbket.company.com" hat 1 Instanzen.
  Instanz "tdbket", Status READY, hat 6 Handler für diesen Dienst...
Dienst "tedab+ket.company.com" hat 1 Instanzen.
  Instanz "tdbket", Status READY, hat 6 Handler für diesen Dienst...
Dienst "tedab.company.com" hat 1 Instanzen.
  Instanz "tdbket", Status READY, hat 6 Handler für diesen Dienst...
Der Befehl wurde erfolgreich ausgeführt.


Why?
This is the default behaviour.
As long as you don't have the default service in your tns_aliasses that are in use it should not be a problem.