Dear Zaxo,
One last thing here. I'm really sorry for not being precise earlier. I was just trying to pose the problem as simple as possible. The element of the array in my actual production code comes with white space like this:

my $HoA = {
            '1,2,flintstones' => [ "fred-1 foo-2", "barney-1 bar-2" ],
            '2,3,jetsons'   => [ "george-1 foo-2", "jane-1 bar-2"],
      };
[download]

The key of the new hash is identified correctly, the problem is only in the values. Is there a way I can modify your code? In particular, so that it takes the element of the array as "one" entity regardless the white-space?
So that it doesn't return:

$VAR1 = [
          {
            '1,2,flintstones' => undef,
            '2,3,jetsons' => undef
          },
          {
            '1,2,flintstones' => 'jane-1',
            '2,3,jetsons' => 'foo-2'
          },
          {
            '1,2,flintstones' => undef,
            '2,3,jetsons' => 'bar}'
          },
          {
            '1,2,flintstones' => 'barney-1',
            '2,3,jetsons' => 'foo-2'
          },
          {
            '1,2,flintstones' => undef,
            '2,3,jetsons' => 'bar-2}'
          }
        ];
[download]

But simply:

my $AoH = [

              {
                '1,2,flinstones' => "fred-1 foo-2",
                '2,3,jetsons'    => "george-1 foo-2"
              },
              {
                '1,2,flinstones' => "fred-1 foo-2",
                '2,3,jetsons'    => "jane-1 bar-2"
              },
              {
                '1,2,flinstones' => "barney-1 bar-2",
                '2,3,jetsons'   => "george-1 foo-2"
              },
              {
                '1,2,flinstones' => "barney-1 bar-2",
                '2,3,jetsons'    => "jane-1 bar-2"
              },

];
[download]

I tried to modify your code by changing the type of separator. But doesn't work either. Hope to hear from you again.