my %in_hash = (
  jibber => [
              {id =>  1, score => 3, name => 'foo'},
              {id =>  5, score => 1, name => 'bar'},
              {id => 22, score => 6, name => 'baz'},
            ],
  jabber => [
              {id =>  3, score => 1, name => 'boo'},
              {id =>  5, score => 3, name => 'bar'},
              {id => 12, score => 2, name => 'zib'},
              {id => 22, score => 2, name => 'baz'},
            ],
);

##</code><code>##


my %out_hash = (
  'jibber jabber' => [
                        {id =>  5, score => 4, name => 'bar'},
                        {id => 22, score => 8, name => 'baz'},
                     ],
  'jibber'        => [
                        {id =>  1, score => 3, name => 'foo'},
                     ],
  'jabber'        => [
                        {id =>  3, score => 1, name => 'boo'},
                        {id => 12, score => 2, name => 'zib'},
                     ],
)