In Oracle, can we restore a database onto the same instance with a different name? In SQL server I can restore a database onto the same instance with a different name. Eg: If there is a database DB_prod, I can take a full backup and restore it on the same instance with a different name like DB_test.

Is a similar task possible with Oracle?
Easily - just use RMAN to clone it. I think you mean in Oracle terminology, clone the database into a new instance on the same server. If you really do mean clone the schema into the same Oracle instance, then the easiest way is Datapump.