Remove duplicated elements of associative array in PHP

$result = array(
    0=>array('a'=>1,'b'=>'Hello'),
    1=>array('a'=>1,'b'=>'other'),
    2=>array('a'=>1,'b'=>'other'),
);

If it is duplicated removed it, so the result is as follows:

$result = array(
    0=>array('a'=>1,'b'=>'Hello'),
    1=>array('a'=>1,'b'=>'other')   
);

Could any know to do this?

Thanks