Problem in parsing XML file using XMl::Twig

ramya2005 has asked for the wisdom of the Perl Monks concerning the following question:

I have the following two XML files.

books.xml

<Books>
   <Titles Mode="List">
    <Title Name="Programming Perl"/>
    <Title Name="Advanced Perl Programming"/>
    <Title Name="Learning Perl on Win32 Systems"/>
   </Titles>
</Books>
[download]

filter.xml

<Filters>
   <Titles>
    <Title Name="Programming Perl"/>
    <Title Name="Advanced Perl Programming"/>
    <Title Name="Learning Perl on Win32 Systems"/>
   </Titles>
</Filters>
[download]

I am trying to do the following using the code below.
1. Change the 'Title Name' in 'books.xml' by appending the existing 'Title Name' with some random number.
2. Change the corresponding 'Title Name' in 'filter.xml'

use XML::Twig;

# Learning XML testing functions
ReadBooksInfo('books.xml','filter.xml');

sub ReadBooksInfo{
   
   my $books_name  = shift;
   my $filter_name = shift;

   my $filter_tree;

   my $books_tree= new XML::Twig(
      TwigHandlers => { 
         Title => 
            sub { 

               my( $titletwig, $title_ele ) = @_;                     
+       my $titlename  = $title_ele->att('Name');                     
               my $unique_titlename = CreateUniqueFilterName($filterna
+me);
   
               print "\nGenerated unique title name:  ", $unique_title
+name; 
               print "\n";
   
               $title_ele->set_att( Name => "$unique_titlename ");
            
               $filter_tree= new XML::Twig(
                  TwigHandlers => {
                     qq[Title[\@Name="$titlename"]] =>
                        sub {
                           my ( $tree, $element ) = @_;

                           $element->set_att( Name => "$unique_titlena
+me" );
                           $element->print;
                        }
                  }
               );

               $filter_tree->parsefile($filter_name);

            }
      }
   );      

   $filter_tree->parsefile( $books_name );     
   $filter_tree->print;                        
   $books_tree->print;                      
}



# Create unique filter names
# ===========================
sub CreateUniqueFilterName { 
   
   my $user_filter_name    = shift;

   my $lower=1000; 
   my $upper=2000000; 
   my $random = int(rand( $upper - $lower + 1 ) ) + $lower; 
   
   my $unique_filter_name = $user_filter_name . "_". "$$". "_". "$^T" 
+. "_" .$random;

}
[download]

Now the problem is I am able to correctly parse the items. But at at the end when I print the 'books_tree - twig' only the Title name 'Learning Perl on Win32 Systems' reflects the changes. Everything else is same as the original books.xml file.

Please tell me how to fix this?

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