Script follows (note two `ldaps://', other things work):

$ds1 = ldap_connect('ldaps://server1.domain.org');
ldap_bind($ds1, 'cn=Manger,o=org,c=RU', 'secret');
$ds2 = ldap_connect('ldaps://server2.domain.org');
ldap_bind($ds2, 'cn=Manger,o=org,c=RU', 'secret');

Configure follows:
./configure \
  --without-pear \
  --disable-xml \
  --prefix=/opt/php4 \
  --with-apxs=/opt/apaches/DSO/bin/apxs \
  --with-mod_charset \
  --enable-shared \
  --disable-static \
  --with-zlib=shared \
  --with-mysql=shared,/opt/mysql \
  --with-ldap=shared,/opt/ldap \
  --with-imap=shared,/usr/local/src/imap-current \
  --with-gd=shared,/opt/gd \
  --enable-mbstring \
  --enable-mbregex

I use dynamic extensions loaded in php.ini.
OpenLDAP is v2.1.3 Release.
PHP is compiled as a DSO (apxs) module for Apache 1.3.26.

The tricky thing is that TLS-specific OpenLDAP options are passed through the environment like this:

LDAPTLS_CACERT=/etc/ca.crt \
LDAPTLS_CERT=/etc/client.crt \
LDAPTLS_KEY=/etc/client.key \
LDAPTLS_REQCERT=hard  /opt/apaches/DSO/bin/httpd 

That script gives me 100%-reproducible core dump.

May be it's better to pass such options by means of php.ini variables (openldap2) ?

=cut
[ldap]
ldap.tls_cacert =
ldap.tls_cert =
ldap.tls_key =
ldap.tls_reqcert =
=cut

Thank You.