Salesforce CollaborationGroup sObject in Apex Unit Tests

The below Test Class Code will occur [System.DmlException: Insert failed. First exception on row 0; first error: DUPLICATE_VALUE] error if a same CollaborationGroup was existed,even Test Class dose not have the @IsTest(SeeAllData=true) annotation.

As the document of Salesforce CollaborationGroup API [SOAP API Developer’s Guide],the Name of CollaborationGroup must be unique across public and private groups.
It seems that although CollaborationGroups are not visible in Unit Test,there still has the unique limit as the real data.