title: exxcel formula to count running duplicates in row
body: <p>Dears,</p>
  
  <p>i want to count running duplicates in my excel for an upload. the target data should be as below:</p>
  
  <pre><code>1021023 0
  1021023 1
  1021023 2
  1021034 0
  1021034 1
  1021039 0
  1021039 1
  1021039 2
  </code></pre>