I am not sure if you need to check the redundancy while entering or you already have the Data stored in Db and you wanted to check the dependency.
If you already have the data stored, When retrieving data from the DB, you can use Report Definition and you can check the option for 'Remove-duplicate rows' option.
If you want to check the redundancy while inserting the content, there are several ways you can acheive the requirement. One such is writing an activity which can do obj-browse and check if it is a duplicate. If no, you can commit into that data class.