Information
Although the groupadd program will not let you create a duplicate Group ID (GID), it is possible for an administrator to manually modify group(4) and change the GID field.
User groups must be assigned unique GIDs for accountability and to ensure appropriate access protections.
Solution
Correct or justify any items discovered in the Audit step. Determine if there exists any duplicate group identifiers, and work with each respective group owner to remediate this issue and ensure that the group ownership of their files are set to an appropriate value.