title: How to output duplicated rows
body: <p>I have the following data:</p>
  
  <pre><code>x1  x2  x3  x4
  34  14  45  53 
  2   8   18  17
  34  14  45  20
  19  78  21  48 
  2   8   18  5
  </code></pre>
  
  <p>In rows 1 and 3; and 2 and 5 the values for columns X1;X2,X3 are equal. How can I output only those 4 rows, with equal numbers? The output should be in the following format:</p>
  
  <pre><code>x1  x2  x3  x4
  34  14  45  53
  34  14  45  20
  2   8   18  17
  2   8   18  5
  </code></pre>
  
  <p>Please, ask me questions if something unclear.</p>
  
  <p>ADDITIONAL QUESTION: in the output</p>
  
  <pre><code>x1  x2  x3  x4
  34  14  45  53
  34  14  45  20
  2   8   18  17
  2   8   18  5
  </code></pre>
  
  <p>find the sum of values in last column: </p>
  
  <pre><code>x1  x2  x3  x4
  34  14  45  73
  2   8   18  22
  </code></pre>