Simple example:
<?php
class Test {}
$test1 = new Test;
$test1_id = spl_object_id( $test1 );
$test2 = new Test;
$test2_id = spl_object_id( $test2 );
var_dump( $test1_id === $test2_id );
var_dump( $test1_id );
var_dump( $test2_id );
?>
Returns
bool(false)
int(5288)
int(5287)