BEGIN {
    $ENV{QUERY_STRING} = 'mode=orig';
    $ENV{REQUEST_METHOD} = 'GET';
}
use CGI qw( hidden );

print hidden( 'mode', 'second arg' ), "\n";
print hidden( -name     => 'mode',
              -default  => 'default', ), "\n";
print hidden( -name     => 'mode',
              -default  => 'forced',
              -override => 1 ), "\n";
__END__
<input type="hidden" name="mode" value="orig"  />
<input type="hidden" name="mode" value="orig"  />
<input type="hidden" name="mode" value="forced"  />