title: Why does inner join result in more rows than the dataframe with lesser rows?
body: <p>I would like to ask why does inner join result in more rows than df_1? I thought that inner_join only retains those rows with customer_id value present in both df_1 and df_6, so the maximum number of rows should be 99441. I do not understand why I get 99455 rows instead? Thank you.</p>
  <p>Please check out my screenshot here: <a href="https://i.stack.imgur.com/4AY8D.png" rel="nofollow noreferrer">https://i.stack.imgur.com/4AY8D.png</a></p>