title: Remove duplicate elements in array
body: <p>i have search SO but most of the results is similar to <a href="https://stackoverflow.com/questions/307674/how-to-remove-duplicate-values-from-a-multi-dimensional-array-in-php">How to remove duplicate values from a multi-dimensional array in PHP</a></p>
  
  <p>i've tried array_unique, but does not work.</p>
  
  <pre><code>  Array
      (
          [0] =&gt; Array
              (
                  [0] =&gt; ball_24.gif
                  [1] =&gt; ball_8.gif
                  [2] =&gt; ball_1.gif
                  [3] =&gt; ball_33.gif
                  [4] =&gt; ball_43.gif
                  [5] =&gt; ball_1.gif
                  [6] =&gt; ball_8.gif
                  [7] =&gt; ball_24.gif
                  [8] =&gt; ball_33.gif
                  [9] =&gt; ball_43.gif
              )
  
      )
  </code></pre>