…
my @loop_names = (); 
foreach my $row (@{$names_data}) {

   my %row_data;
   
   $row_data{NAMES} = $row->{NAMES} || '';

   push(@loop_names, \%row_data);
   
}
# Dumper of @loop_names;
=code
 $VAR1 = {
           'NAMES' => 'John Doe'
         };
 $VAR2 = {
           'NAMES' => 'Mary Lou'
         }
=cut

##</code><code>##

my @loop_addr = ();
 foreach my $row (@{$all_party_id_data}) {

   my %row_data;

   $row_data{FULL_NAME} = $row->{FULL_NAME} || '';
   $row_data{ADDR}      = $row->{ADDR}      || '';
   $row_data{ZIP}       = $row->{ZIP}       || '';

   warn Dumper $row_data{FULL_NAME}; # it will get "Mary Lou"

   # I just want @loop_names to have what is unique
   @loop_names = map /$row_data{FULL_NAME}/ ? () : $_, @loop_names;
   
   $row_data{N_DATA} = \@loop_names;

   push(@loop_addr, \%row_data);
}

# Dumper of @loop_addr
=code
$VAR1 = {

    'FULL_NAME' => 'Mary Lou',
    'ADDR' => '100 - Main Street',
    'ZIP' => '12345',
    'EMAIL_DATA' => [
                      {
                        'NAMES' => 'John Doe'
                      },
                      {
                        'NAMES' => 'Mary Lou' # this shouldn't be here 
                      }
                    ],

        };
=cut

##</code><code>##

$VAR1 = {

    'FULL_NAME' => 'Mary Lou',
    'ADDR' => '100 - Main Street',
    'ZIP' => '12345',
    'EMAIL_DATA' => [
                      {
                        'NAMES' => 'John Doe'
                      },
                    ],

        };