title: How two people can commit in a particular PR
body: <p>I have been contributing to an open source project for a while now, I know most of the <code>Git's Workflow</code>, but recently I founded an interesting thing
  while I was looking at another contributor's <code>PR</code>, I saw two people's image on the <code>commit</code>, when I clicked on the commit it said</p>
  
  <p><code>xyz committed with abc</code></p>
  
  <p>What does that mean ? How can another person commit with another person in his <code>PR</code>, I found it a bit interesting and confusing, therefore thought to ask here.  </p>