[ We'll both have an easier time if you use <c>...</c> around your code. ]

The key to repeating the same action for multiple inputs is to store the inputs in a hash or array, not 12 variables.

use strict;
use warnings;

sub compare_arrays {
   my ($array1, $array2) = @_;

   return 0 if @$array1 != @$array2;
   
   for my $i (0..$#$array1) {
      return 0 if $array1->[$i] ne $array2->[$i];
   }
   
   return 1;
}


my %lists = (
   D => [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9                            ],
   E => [qq( a b c d e f g h i j k l m n o p q r s t u v w x y z )],
   F => [ 1, 3, 5, 7, 9                                           ],
   G => [qq( a b c d e f g h i j k l m                           )],
   H => [ 2, 4, 6, 8                                              ],
   K => [qq( n o p q r s t u v w x y z                           )],
   M => [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9                            ],
   P => [qq( a b c d e f g h i j k l m n o p q r s t u v w x y z )],
   S => [ 1, 3, 5, 7, 9                                           ],
   T => [qq( a b c d e f g h i j k l m                           )],
   X => [ 2, 4, 6, 8                                              ],
   Z => [qq( n o p q r s t u v w x y z                           )],
);

my @keys = keys %lists;

for my $i1 (0..$#keys) {
   my $key1 = $keys[$i1];

   for my $i2 ($i1+1..$#keys) {
      my $key2 = $keys[$i2];
      if ( compare_arrays($lists{$key1}, $lists{$key2}) ) {
         print("$key1 is identical to $key2\n");
      } else {
         #print("$key1 is different than $key2\n");
      }
   }
}
[download]

S is identical to F
T is identical to G
X is identical to H
P is identical to E
K is identical to Z
M is identical to D
[download]

The reason for using

my @keys = keys %lists;

for my $i1 (0..$#keys) {
   my $key1 = $keys[$i1];

   for my $i2 ($i1+1..$#keys) {
      my $key2 = $keys[$i2];
[download]

instead of

for my $key1 (keys %lists) {
   for my $key2 (keys %lists) {
[download]

is to avoid useless duplication of outputs.