PHP の array_unique で多次元配列の重複削除できるか

1.php

<?php
$a = array(
  array(1,2,3),
  array(1,2,3),
  array(4,5,6),
);
print_r(array_unique($a));

// Array
// (
//   [0] => Array
//     (
//       [0] => 1
//       [1] => 2
//       [2] => 3
//     ) 
// )

2.php

<?php
$a = array(
  array(1,2,3),
  array(1,2,3),
  array(4,5,6),
);
print_r(array_unique($a, SORT_REGULAR));

3.php

<?php
$a = array(
  array(1,2,3,array(4,5)),
  array(1,2,3,array(4,5)),
  array(4,5,6,array(7,8)),
);
print_r(array_unique($a, SORT_REGULAR));

4.php

<?php
$a = array(
  array('a'=>1, 'b'=>2),
  array('a'=>1, 'b'=>2),
  array('a'=>2, 'b'=>3),
);
print_r(array_unique($a, SORT_REGULAR));

5.php

<?php
$a = array(
  array('a'=>1, 'b'=>2, 'c'=>array('d'=>3,'e'=>4)),
  array('a'=>1, 'b'=>2, 'c'=>array('d'=>3,'e'=>4)),
  array('a'=>2, 'b'=>3),
);
print_r(array_unique($a, SORT_REGULAR));

6.php

<?php
$a = array(
  array('a'=>1, 'b'=>2, 'c'=>array('d'=>3,'e'=>4)),
  array('b'=>2, 'a'=>1, 'c'=>array('e'=>4,'d'=>3)),
  array('a'=>2, 'b'=>3),
);
print_r(array_unique($a, SORT_REGULAR));

7.php

<?php
$a = array(
  array('a'=>1, 'b'=>2),
  array('a'=>1, 'b'=>2),
  array('a'=>2, 'b'=>3),
);
$tmp = array();
foreach($a as $val) {
  if (!in_array($val, $tmp)) {
    $tmp[] = $val;
  }
}
print_r($tmp);