When importing a large number of users into Active Directory it is possible that 2 or more users will share the same name. When using AD Bulk Users the users first name (givenName attribute) and second name (sn attribute) are used internally by the program to construct the Common-Name (cn attribute), this cn value is used by Active Directory to construct the distinguishedName which has to be unique as its value is the path to the user object, for example ‘CN=John Smith,OU=Managers,DC=domain,DC=com’.