title: search and delete duplicate entries inside a file for a line
body: <p>I have an file with the below content </p>
  
  <pre><code>OPTIONS='--selinux-enabled -G dockerroot -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --insecure-registry my-demo-auto-images-releases-dev.cto.com --insecure-registry my-demo-auto-images-stable-dev.cto.com --insecure-registry my-demo-auto-images-releases-dev.cto.com --insecure-registry my-demo-auto-images-stable-dev.cto.com --insecure-registry my-demo-auto-images-snapshots-dev.cto.com'
  DOCKER_CERT_PATH=/etc/docker
  </code></pre>
  
  <p>There are duplicate entries for <code>--insecure-registry my-demo-auto-images-releases-dev.cto.com</code> and <code>--insecure-registry my-demo-auto-images-stable-dev.cto.com</code>  i need to keep only one occurrence of above entries.</p>
  
  <p>file should look like this</p>
  
  <pre><code>OPTIONS='--selinux-enabled -G dockerroot -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --insecure-registry my-demo-auto-images-releases-dev.cto.com --insecure-registry my-demo-auto-images-stable-dev.cto.com --insecure-registry my-demo-auto-images-snapshots-dev.cto.com'
  DOCKER_CERT_PATH=/etc/docker
  </code></pre>
  
  <p>Entries can be in any order.</p>