how to get older version of php5-mbstring

[Pieter Donche]

I updated via the ports collection php5-mbstring
to the latest version 5.2.9. Previously I had 5.2.8

Also updated php5 from 5.2.8 to 5.2.9
and php5-extensions from 1.2 to 1.3

installing php5-mbstring-5.2.9 installed it alongside php5-mbstring-5.2.8:
# pkg_info | grep mbstring
php5-mbstring-5.2.8 The mbstring shared extension for php
php5-mbstring-5.2.9 The mbstring shared extension for php

Then I deleted mbstring 5.2.8 (thinking I wouldn't need it any longer)
# pkg_delete php5-mbstring-5.2.8

But now it seems that my Drupal 6.9 continues to look for 
php5-mbstring-5.2.8 (not looking at php5-mbstring-5.2.9)

How can I install php5-mbstring-5.2.8 again via the ports ??