yitzchak on the CB made me realize I may have misunderstood what you were doing:

use strict;
use warnings;

use Data::Dumper;
use WWW::Mechanize;

my %links;
for my $cnt (1..3)
{
   my $url = "http://www.foo.com/p/$cnt";
   my $mech = WWW::Mechanize->new();
   $mech->get($url) or die "no such url";
   my @link = $mech->find_all_links(tag => "a", class => "foo") or die
+ "can't find link";
   $links{$cnt} = \@link;
}
# Do something with @link here, after the loop is done
print Dumper \%link; # Show the content of %link
[download]

The output of Data::Dumper should allow you to find which version suits your needs the best.