use strict; 
use warnings;
use URI;
use Data::Dumper;
use Tie::Hash::MultiVal;

my $uri = URI->new('http://foo.com/bar.cgi?foo=bar&foo=baz&bar=qux&baz=qux');
my %hash;
tie %hash, 'MyHash';

%hash = $uri->query_form();
@hash{qw(foo bar baz qux)} = qw(one two three four);

delete $hash{foo};
print Dumper \%hash;