title: Renaming duplicate strings in R
body: <p>I have an R dataframe that has two columns of strings. In one of the columns (say, Column1) there are duplicate values. I need to relabel that column so that it would have the duplicated strings renamed with ordered suffixes, like in the Column1.new</p>
  
  <pre><code> Column1   Column2   Column1.new
   1         A         1_1
   1         B         1_2
   2         C         2_1
   2         D         2_2
   3         E         3
   4         F         4
  </code></pre>
  
  <p>Any ideas of how to do this would be appreciated.</p>
  
  <p>Cheers,</p>
  
  <p>Antti</p>