title: rbind data frames in R, possible to add more than a number to duplicated rownames?
body: <p>When using rbind in R to combine two data frames with an identical row name it adds &quot;1&quot; to the second row name.</p>
  <pre><code>df1 = data.frame(A=1:3,B=1:3)
  df2 = data.frame(A=1:3,B=1:3)
  
  rownames(df1) = c(&quot;A1&quot;,&quot;B1&quot;,&quot;C1&quot;)
  rownames(df2) = c(&quot;C1&quot;,&quot;C2&quot;,&quot;C3&quot;)
  
  rbind(df1,df2)
  
  # A B
  # A1  1 1
  # B1  2 2
  # C1  3 3
  # C11 1 1
  # C2  2 2
  # C3  3 3
  </code></pre>
  <p>However, in my case the row names already contain letters with numbers (gene names), so adding an additional &quot;1&quot; change C from number 1 to number 11. Is there a way to force rbind to for instance add an additional dot or underline so &quot;C1&quot; becomes &quot;C1.1&quot; or &quot;C1_1&quot; instead of &quot;C11&quot;?</p>