Groups> Manage Roles>Add a Role>Enter an already exisitng role name and click Save.Then a message, 'groups.roles.create.notunique ' is shown.

Beta site>Groups> Manage Roles
Click Add a Role button.
Enter an already exisitng role name and click Save.
Then a message, 'groups.roles.create.notunique ' is shown.

This issue is there in dev site also.