如何仅比较存储在数组中的行中的某些单元格

Got a strange situation and I don't know how to figure it out. Let's see if you can give me a hint!

I've built an array with rows in his content like this and want to delete duplicates:

echo $nodup_filter[1];

<tr>
<td>29/06/2015</td>
<td>09:00</td>
<td>29/06/2015</td>
<td>12:00</td>
<td>3</td>
<td>code 1</td>
<td>1007 Additional information 5</td>
<td>109 Additional information 6</td>
<td>Additional information 7</td>
<td>Additional information 8</td>
<td> </td>
</tr>

echo $nodup_filter[2];

<tr>
<td>12/02/2015</td>
<td>16:00</td>
<td>14/04/2015</td>
<td>18:00</td>
<td>2</td>
<td>Code 2</td>
<td>Additional information 1</td>
<td>Additional information 2</td>
<td>Additional information 3</td>
<td>Additional information 4</td>
<td> </td>
</tr>

echo $nodup_filter[3];

 <tr>
<td>29/06/2015</td>
<td>09:00</td>
<td>29/06/2015</td>
<td>12:00</td>
<td>3</td>
<td>code 1</td>
<td>1007 Additional information 5</td>
<td>109 Additional information 6</td>
<td>Additional information 7</td>
<td>Additional information 8</td>
<td> </td>
</tr>

And so on and so forth...

What I want is to compare the entire array, but only from the sixth cell to the end of every array position.

I want to compare this:

<td>code 1</td>
<td>1007 Additional information 5</td>
<td>109 Additional information 6</td>
<td>Additional information 7</td>
<td>Additional information 8</td>
<td> </td>

With this:

<td>Code 2</td>
<td>Additional information 1</td>
<td>Additional information 2</td>
<td>Additional information 3</td>
<td>Additional information 4</td>
<td> </td>

And with this:

<td>code 1</td>
<td>1007 Additional information 5</td>
<td>109 Additional information 6</td>
<td>Additional information 7</td>
<td>Additional information 8</td>
<td> </td>

And if there is a match, delete the duplicate array position. As you can see the $nodup_filter[1]; and $nodup_filter[3]; got the same information from his sixth cell to the end of the row, so one of them ($nodup_filter[1] or $nodup_filter[3]) need to be deleted. And then, continue compairing with the next array position..

Beforehand, thanks a lot for your help and time.

Since you have it in array you can loop and check the content of only from the sixth cell text, one way to doing this will be this

$unique_array = array();
foreach($data as $k=>$v) {
   // assuming $data[$k][6] sixth cell
   if( in_array($data[$k][6], $unique_array) ) { 
      //remove duplicate 
      unset($data[$k]);
   }else {
     //Push it to final array 
     array_push($unique_array, $v);
   }
}