Hi,
because authentication is set on the instance level, I could probably do the following:
1. Create first instance and set authentication to operating system. Create database inside this instance.
2. Create second instance and set authentication to LDAP system. Create database inside this instance.
3. Create federated access from one database to another and set federated authentication to no.

But I am looking for something simpler. Is there any simpler solution?
Regards