Create a list that contains duplicates and unique names and no blanks

Sorry, revised formula

=IF(ISERROR(INDEX($AF$4:$AF$25,SMALL(IF(($AF$4:$AF$25<>"")*(COUNTIF($AH$3:$AH3,$AF$4:$AF$25)=0),ROW($AF$4:$AF$25),""),1)-ROW($AF$4)+1)),"",INDEX($AF$4:$AF$25,SMALL(IF(($AF$4:$AF$25<>"")*(COUNTIF($AH$3:$AH3,$AF$4:$AF$25)=0),ROW($AF$4:$AF$25),""),1)-ROW($AF$4)+1))