Right now `results` could be multiple records of the same model.

~~~ php
$foo = array(
	'children_ids' => array(1,2,3),
);
$bar = array(
	'children_ids' => array(2,3,4),
);
~~~

This will do a single query
~~~
array(
	'conditions' => array(
		'_id' => array(
			'$in' => array(
				1,2,3,2,3,4
			),
		),
	),
)
~~~

Instead of 1 queries for each record.

~~~
array(
	'conditions' => array(
		'_id' => array(
			'$in' => array(
				1,2,3
			),
		),
	),
)
array(
	'conditions' => array(
		'_id' => array(
			'$in' => array(
				2,3,4
			),
		),
	),
)
~~~