my @data = qw[
  111011001010011110100010100001
  111010000010010110000010000001
  000101011100001000110101110000
  000101111101001001111101111110
  111011001010111110100010100001
  000100010100000000010001010000
];

use Data::Dumper;

for my $i (0 .. $#data) {
  for my $j ($i+1 .. $#data) {

    my %counts;

    $counts{ substr($data[$i],$_,1) . substr($data[$j],$_,1) }++
        for 0 .. length($data[$i]) - 1;

    print Dumper \%counts;

  }
}