title: How to rename a duplicate column using column index?
body: <p>I have a dataframe that has two same name columns, since the first column (agreementID) holds a value, I want to rename the second column) which holds null values to a different name, and different records. I want to use the aggrementID as a key in the future.</p>
  
  <p><a href="https://i.stack.imgur.com/X8SLE.png" rel="nofollow noreferrer">enter image description here</a>
  <a href="https://i.stack.imgur.com/2voA1.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <p>Please help on how to rename the column using column position ore index?</p>