open (DATA, $results) || die "couldn't open the file!";
my %unique = ();
while( <DATA> ){
  chomp;
  $unique{ join( "\t", sort split /\t/ ) } ++;
}

my @pairs = ();
my @not_pairs = ();
for my $item (sort keys %unique ){
  if( $unique{$item} > 1 ){
    push @pairs, $item;
  }else{
    push @not_pairs, $item;
  }
}
print join( "\n", @pairs ), "\n";