title: Highlight duplicate cell values in different colours
body: <p>I'm using conditional formatting to highlight duplicate cells, but I have up to 5 instances of a duplicated value. How can I apply a separate colour to each duplicated cell?</p>
  
  <p>So if I have 5 instances of ABC123, how can the first instance be red, the second green, the third blue, fourth yellow, fifth orange (or whatever colours)?</p>