title: Remove one of each pair of duplicates (row) in values paired in two columns
body: <p>I have two columns from which I need to remove duplicate rows. For this example:</p>
  
  <pre><code>A                b
  sport 1          pippo
  sport 1          pippo
  sport 1          pluto
  sport 2          paperino
  sport 2          paperino   
  sport 3          gastone
  </code></pre>
  
  <p>my required output is:</p>
  
  <pre><code>A                b
  sport 1          pippo
  sport 1          pluto
  sport 2          paperino  
  sport 3          gastone
  </code></pre>
  
  <p>I'm new to Excel so don't know what kind of formula or VBA to use.</p>
  
  <p>How might I achieve this?</p>