title: Remove duplicates in dataframe pandas based on values of two columns
body: <p>I have a dataframe of customers with some items, which looks like this:</p>
  
  <pre><code>Customer ID     Item
       1         Banana
       1         Apple
       2         Orange
       3         Grape
       4         Banana
       4         Apple
       5         Orange
       5         Grape
       6         Orange
  </code></pre>
  
  <p>What I'm willing to do is to remove all duplicates customers with same items, so the results should look like this:</p>
  
  <pre><code>Customer ID     Item
       1         Banana
       1         Apple
       2         Orange
       3         Grape
       5         Orange
       5         Grape
  </code></pre>
  
  <p>As customer 4 has the same items as customer 1. Also customer 6  with 2. </p>
  
  <p>Thanks in advance for your help!</p>