title: How to remove duplicate text files with different names from a directory using diff?
body: <p>I have a directory of some text files. These files may not have unique content. I want to keep only unique files and delete others.</p>
  
  <p>I tried the following:</p>
  
  <pre><code>diff -sr directory/ copy-of-directory/
  </code></pre>
  
  <p>which returns:<br>
  Files directory/1.txt and copy-of-directory/1.txt are identical<br>
  Files directory/2.txt and copy-of-directory/2.txt are identical<br>
  Files directory/3.txt and copy-of-directory/3.txt are identical ...  </p>
  
  <p>but why does it not say (I confirmed that 1.txt and 2.txt do differ)<br>
  Files directory/1.txt and copy-of-directory/2.txt differ</p>