foreach $group_id (keys  %data) {
     @temp = sort keys %{ $data{$group_id} };
     $my_hoa{$group_id}{'ordered'} = [ @temp ];
}

foreach $group_id (sort keys  %my_hoa) {
     for $i (0 .. $#{ @{ $my_hoa{$group_id}{'ordered'} } }) {
          # output some stuff;
     }
}