While I would be inclined to use the light-weight solution of creating more schemas, oracle also allows you to create multiple independent databases on the same server. You can use an Oracle utility called DBCA (Database Creation Assistant) to do so. You can even use an existing database as a template for new databases.

Each database can be connected to separately via a different SID (SIDs usually are the same as the database name).

The advantage of the using separate databases is that, indeed, the usernames are unique within databases, but could be the same to users in other databases if that is a hangup for your scripts.

While schemas within a database can share tablespaces, storage between databases is not shared this way.

Database linking can be done between schemas in a single database or to schemas in another database.