title: Tableau Filtering on duplicates
body: <p>I have a dataset that looks similar to this:</p>
  
  <p><img src="https://i.stack.imgur.com/l6h5C.png" alt="enter image description here"></p>
  
  <p>As you can see some ABNs have multiple business names attached while others have just one.
  I want to create a filter that allows the user to see just those rows where there are multiple names to each ABN.
  For example, a filer that will filter out ABN 456.</p>
  
  <p>I can imagine how I would write that in SQL, but cannot get my head around how to do it in Tableau.
  Any help would be appreciated.</p>