Hi! I need help in merging the difference between two files based on the same content within them and sorting and saving in the third file following are my example files:

File1:
NAME, ID1, ID2
apple
banana

NAME, ID1, ID3
strawberry
grape

File 2:
NAME, ID1, ID2
apple
jackfruit

NAME, ID1, ID4
banana
grapes


Desired output result:

NAME, ID1, ID2
apple
banana

NAME, ID1, ID3
strawberry
grape

NAME, ID1, ID4
banana
grapes

However, this is what I get: 
NAME, ID1, ID2
NAME, ID1, ID3
NAME, ID1, ID4

#!/bin/perl -w
use strict;
use warnings;
use File::Copy;
use Cwd;
my $dir = cwd;
main();
sub main
{
    printf "\nStarting script\n";
    printf "\nEnter file 1: ";
    my $a = <STDIN>;
    chomp $a;
    printf "\n";
    printf "Enter file 2: ";
    my $b = <STDIN>;
    chomp $b;
    my $output = "output.txt";
    
    if(-e $a and -e $b) 
        {
            my $counter = 0;
            my $counter2 = 0; 
            my %results = (); 
            open (FILEA, "<$a") or die "Input file $a not found.\n";
            while(my $line = <FILEA>)
            {
                $counter++;
                if($line =~ /^NAME/)
                {
                    my ($name, $variable1, $variable2) = split(',', $l
+ine, 3);
                    $results{$line}=1;
                }
            }
            close(FILEA); 

            open (FILEB, "<$b") or die "Input file $b not found.\n";
            while(my $line =<FILEB>) 
            { 
                if($line =~ /^NAME/)
                {
                    my ($name, $variable1, $variable2) = split(',', $l
+ine, 3);
                    $results{$line}++;
                }
            }    
            close(FILEB);  

            open (OUTPUT, ">$output") or die "Cannot open $output for 
+writing \n";
            foreach my $line (keys %results) 
            {
                   print OUTPUT "$line";
                $counter = $counter if $counter != $counter2;
            }
            close OUTPUT;        
        }
}
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I am new to perl so please someone could help me and direct me to the right direction.

Thanks so much in advance.