#!/usr/bin/perl

use strict;
use warnings;
           
my $bal;

$bal = qr /[^()]*
           (?: [(] (??{ $bal }) [)] )*
           [^()]*/x;
 
while (<DATA>) {
    chomp;
    print $& while /$bal/g;
    print "\n";
}


__DATA__   
(1.3.56.84 
56.38.m.26)
(56.2.3.59)
((one)(two))
((one(two))  
((one)(two)
(one)(two))
((one)two))

##</code><code>##

1.3.56.84
56.38.m.26
(56.2.3.59)
((one)(two))
(one(two))
(one)(two)
(one)(two)
((one)two)