while (<DATA>) {
  chomp;
  my $key = lc $_;
  next if $seen{$key}++;
  my $signature = join "", sort split //, $key;
  push @{$words{$signature}}, $_;
}
for (sort keys %words) {
  my @list = sort @{$words{$_}};
  next unless @list > 1;
  print "@list\n";
}
##</code><code>##

ab
aabb
aaabbb
xxyy
xxxyyy

##</code><code>##

ab aabb aaabbb
xxyy xxxyyy
##</code><code>##

#!/usr/bin/perl

while (<DATA>) {
  chomp;
  my $key = lc $_;
  next if $seen{$key}++;
  
  my @unique     = ();
  my %seenletter = ();
  my @alphawithdupes = sort split //, $key;
  
  foreach my $elem ( @alphawithdupes ) {
    	next if $seenletter { $elem }++;
    	push @unique, $elem;
  }
  
  my $signature = join "", @unique;
  push @{$words{$signature}}, $_;
}
for (sort keys %words) {
  my @list = sort @{$words{$_}};
  next unless @list > 1;
  print "@list\n";
}
__END__
ab
aabb
aaabbb
xxyy
xxxyyy