title: Git: remove a duplicate commit
body: <p>I don't know how but I have the following log :</p>
  
  <pre><code>* 527795c - (HEAD, origin/master, master)
  *   b829011 - Merge branch 'master'
  |\  
  | * 423e3aa - Some files added
  | * b4c60f2 - Initial commit
  * a838a27 - Initial commit
  </code></pre>
  
  <p>Commits <code>a838a27</code> and <code>b4c60f2</code> are the same (all the modifications are exactly the same).</p>
  
  <p>How I can remove commit <code>a838a27</code></p>
  
  <p>Thanks</p>