Two the same pids, possibe?

Hiya according to: http://www.php.net/manual/function.getmypid.php "Note that when running as a server module, separate invocations of the script are not guaranteed to have distinct pids." Can somebody explain me how 2 scripts can have the same pid? (Thats how I read it) P.S. i don't say it will be that way, I only read it "as is possible" and was wondering how that could be Greetz, Tnx in advance Wico