title: finding duplicates and combining part of cell value next to duplicate
body: <p>Let's start with an example of how some values in my workbook look like:</p>
  
  <pre>
         A        B         C
  1     14-001   2014G001
  2     14-002   2014G002
  3     14-001   2014I002
  </pre>
  
  <p>I want to make a script that copies the values in column B to C, and combines the last 4 characters of these values if the cell value in column A are the same. after running the script it should look like:</p>
  
  <pre>
         A        B         C
  1     14-001   2014G001   G001/I001
  2     14-002   2014G002   G002
  3     14-001   2014I001
  </pre>
  
  <p>I never had to look for duplicates and I can't find a similar problem on the net. Can somebody help me out?</p>
  
  <p>Thanks!!</p>