spl_object_hash not hashing unqiue objects BUG

I am having a problem with spl_object_hash() creating non unique hashes. I understand with MD5 it is possible to have the same hash for different strings but this doesn't seem like that problem. I have created a simple test below, should I report this as a bug or am I doing something wrong. PHP 5.2.8 (extensions all disabled) Win XP SP3 Apache 2.2.11 <?php class a1 {} $obi = new a1(); echo get_class($obi).': '.spl_object_hash($obi).'<br/>'; class a2 {} $obi = new a2(); echo get_class($obi).': '.spl_object_hash($obi).'<br/>'; class a3 {} $obi = new a3(); echo get_class($obi).': '.spl_object_hash($obi).'<br/>'; unset($obi); class a4 {} $obi = new a4(); echo get_class($obi).': '.spl_object_hash($obi).'<br/>'; ?> Outputs: a1: 09d264fcececf51c822c9382b40e3edf a2: 45701af64172cbc2a33069dfed73fd07 a3: 09d264fcececf51c822c9382b40e3edf a4: 09d264fcececf51c822c9382b40e3edf Thanks let me know how I should proceed with this.