foreach $key_1 (keys %hash_1) {
   foreach $key_2 (keys %hash_2) {
      $my_hash{$key_1}{$key_2} = something;
   }
}
........
$vars = {
   my_hash= > \%my_hash
}

##</code><code>##

[% FOREACH key_1 IN my_hash.keys.sort.reverse %]
   [% FOREACH key_2 IN my_hash.$key_1.keys.sort.reverse %]
      output something
   [%END%]
[%END%]

##</code><code>##

[% FOREACH key_1 IN my_hash.keys.sort %]
   [% FOREACH key_2 IN my_hash.$key_1.keys.sort %]
      output something
   [%END%]
[%END%]

##</code><code>##

[% IF sort_order == 1 %]
   [% FOREACH key_1 IN my_hash.keys.sort %]
      [% FOREACH key_2 IN my_hash.$key_1.keys.sort %]
         output something
      [%END%]
   [%END%]
[% ELSE %]
   [% FOREACH key_1 IN my_hash.keys.sort.reverse %]
      [% FOREACH key_2 IN my_hash.$key_1.keys.sort.reverse %]
         output something
      [%END%]
   [%END%]
[%END%]

##</code><code>##

[% FOREACH key_1 IN my_hash.keys.variable_sort_order %]
   [% FOREACH key_2 IN my_hash.$key_1.keys.variable_sort_order %]
      output something
   [%END%]
[%END%]