my $XML = <<'*END*';
<root>
 <sub>
   <a>foo</a>
   <a>bar</a>
   <b>blah</b>
 </sub>
 <sub>
   <a>baz</a>
   <b x="4">blah blah</b>
 </sub>
</root>
*END*

use XML::Simple;
use Data::Dumper;

my $ref = XMLin( $XML);
print Dumper($ref);
__END__