title: awk - Find duplicate records in multiple files
body: <p>I want to find duplicated records in third column of one file (f1) with multiple files (f2,f3,....fn) and print result against every row (in new column) with format: Filename/FirstColumn</p>
  
  <pre><code>f1
  1. 11:10 *Jane&gt; login
  2. 11:15 *Bob&gt;  login
     11:16 *Bob&gt;  logout
  3. 11:45 *Jane&gt; login
  4. 01:20 *John&gt;  login
  5. 02:30 *Deborah  logout
  
  f2
  1. 12:10 *Jane&gt; login
  2. 13:00 *Dorothy  logout
  3. 13:15 *Bob&gt;  login
     14:16 *Bob&gt;  logout
  4. 15:45 *Jane&gt; login
  5. 06:20 *John&gt;  login
  
  f3
  1. 15:10 *Jane&gt; login
  2. 15:50 *Mark&gt; login
  3. 16:10 *Dorothy  logout
  4. 17:18 *Bob&gt;  login
     18:16 *Bob&gt;  logout
  5. 19:45 *Jane&gt; login
  6. 20:21 *John&gt;  login
  </code></pre>
  
  <p>output to f1-dup</p>
  
  <pre><code>f1-dup
  1. 11:10 *Jane&gt; login    f1/1,3_f2/1,4_f3/1,5
  2. 11:15 *Bob&gt;  login    f1/2_f2/3_f3/4
     11:16 *Bob&gt;  logout
  3. 11:45 *Jane&gt; login    f1/1,3_f2/1,4_f3/1,5
  4. 01:20 *John&gt;  login   f1/4_f2/5_f3/6
  5. 02:30 *Deborah  logout
  </code></pre>
  
  <p>I tried several methods but none of them works for me.</p>