Slash after script name in URL

Slash after script name in URL

My own site has one weird bug: I can put anything with slash in the end of
URL and it doesn't show 404 error, it working fine. For example:
That is normal URL: http://site.com/path/index.php
I put "/aaa.php" in the end: http://site.com/path/index.php/aaa.php - and
it show me normal URL (like in 1).
What is it? How to remove this behaviour? I want to see 404 error in
second case.
Apache/2.2.24 (FreeBSD) PHP 5.4.10