I nned to set up a portal, which is used by multiple client, where users can have the same name.
Something like "Miller" at CorpA and "Miller" at CorpB.
They also have different role/group assignements and are diffent legal entities.
On the logon screen, they need to enter their user id and their Organisation as distinction.
Any other tips from other installations?
I dont think that Portal UME Database can do this. You may have to use LDAP integrated User Management in order to do this. You can integrate Portal UME with a supported LDAP. For example, MS Active Directory, Novell eDirectory, SUNs LDAP. IF you are currently using one of them, you can easily integrate it with portal.