When Active Directory LDAP provider is created in Admin console (User Federation), a number of LDAP mappers is automatically added/created for it. Most of the mappers are of type user-attribute-ldap-mapper....

During creation, If I leave the default User attribute name as cn, I see first name and last name LDAP mappers being created...

But if I choose sAMAccountName as User attribute name, I see last name but not first name mapper. In this case there is full name mapper created with type full-name-ldap-mapper

Why the difference here?
Do I need to manually add first name mapper when using User attribute name = sAMAccountName ?
Or should I remove last name mapper if full name itself is enough?

I am currently adding first name mapper and am not seeing any issues but was just curious