title: Searching for an exact repeated sequence (and removing all duplicates) using a PHP regex
body: <p>I'm looking for a regex that will find an exact repeating pattern (case-sensitive).  For instance, middle initials in a name string. Examples:  </p>
  
  <ul>
  <li>Jim G G Bob  is a match on " G " x 2</li>
  <li>Jim G. G. Bob is a match on " G. " x 2</li>
  <li>Tom H H H Ford is a match on " H " x 3 and so on ...</li>
  <li>Sarah H Howard is NOT a match because we have "h ", "H ", and " H" (which are all unique)</li>
  </ul>
  
  <p>I only want to keep the 1st occurrence and remove all others. What will find and remove exact duplicates?</p>