title: SQL Server Finding Duplicates
body: <p>Say I have a table as follows</p>
  
  <pre><code>Employee    RecNumber
  Joe Bloggs  123456
  Joe Bloggs  123456
  Bob Bloggs  123457
  Dup Bloggs  123456
  </code></pre>
  
  <p>And I just want to return all Rec Numbers where 2 People have had the same RecNumber which shouldn't happen.
  Note that one person can have same request number multiple times I just want returned where 2 people have the same rec Number</p>
  
  <p>So all I want returned is</p>
  
  <pre><code>123456
  </code></pre>