strange php on debian

I am working on setting up a php apache mysql debian box for a friend.
I am not a php programmer but there is something strange going on. On a
machine with php 4.1.7 compiled from source the
require_once("file.db.php");
works but useing the debian package it doesn't seem to work right.
unless it has only one dot in the file name like:
require_once("filedb.php");
is this a php compile option of some kind? This just doesn't seem
right. Does anyone know what I'm talking about.

Thanks
--
Bill Warner <wwarner@direct-alliance.com>
Direct Alliance