title: Finding Duplicates (Regex)
body: <p>I have a CSV containing list of 500 members with their phone numbers. I tried diff tools but none can seem to find duplicates. </p>
  
  <p>Can I use regex to find duplicate rows by members' phone numbers?</p>
  
  <p>I'm using Textmate on Mac.</p>
  
  <p>Many thanks</p>