title: Append text to existing target cell in Excel
body: <p>I have a large data set based on tag numbers:</p>
  
  <pre><code>tag    | value 1 | value 2 | ...     | value 20| comment    |
  ------------------------------------------------------------
  01     | data    | data    | data    | data    | red        |
  02     | data    | data    | data    | data    | blue       |   
  03     | data    | data    | data    | data    | purple     |
  04     | data    | data    | data    | data    | green      |
  04     | data    | data    | data    | data    | green      |
  .
  .
  03     | data    | data    | data    | data    | purple     |
  </code></pre>
  
  <p>I would like to check the 'tag' column for duplicate values, and if found, append the word 'duplicate' to the comment, without using an extra column for the calculation. For the table above, the result would be:</p>
  
  <pre><code>tag    | value 1 | value 2 | ...     | value 20| comment            |
  --------------------------------------------------------------------
  01     | data    | data    | data    | data    | red                |
  02     | data    | data    | data    | data    | blue               |   
  03     | data    | data    | data    | data    | purple             |
  04     | data    | data    | data    | data    | green              |
  04     | data    | data    | data    | data    | green - duplicate  |
  .
  .
  03     | data    | data    | data    | data    | purple - duplicate |
  </code></pre>
  
  <p>Is this possible? If so, please provide an example.</p>