title: array_unique for arrays inside array
body: <p>I need a function like <code>array_unique</code> for arrays inside array.</p>
  
  <p>The Case - should be equal, but output "not equal":</p>
  
  <pre><code>&lt;?php
  $arr=array(array('a',1),array('a',2));
  $arr2=array_unique($arr);
  if($arr2==$arr){
    echo "equal";
  }
  else{
    echo "not equal";
  }
  ?&gt;
  </code></pre>
  
  <p>How should the code be changed to get output "equal"?</p>