If this test fails, it means that the repository returned a proper OAI ListSets
response containing set information, but one or more of the setSpec identifiers are duplicated. The Gateway cannot work properly with duplicate setSpec identifiers because those are used to differentiate the collections in the repository. The user will not be allowed to add the repository with duplicate setSpec identifiers.
There is more information on the ListSets verb. There is more information on errors that can come up when adding a new repositories to the Digital Collection Gateway.