title: DataFrame creation - reindexing
body: <p>I keep getting this error in pandas:</p>
  
  <pre><code>raise Exception('Reindexing only valid with uniquely valued Index '
  Exception: Reindexing only valid with uniquely valued Index objects
  </code></pre>
  
  <p>Which I understand will happen if the column names are the same while trying to make a <code>DataFrame</code> from a dictionary.</p>
  
  <p>However, mine are not.</p>
  
  <p>Here is the dictionary I am using - which looks something like this - quite like that given in the tutorial, does not work:</p>
  
  <pre><code>d = {'Sample1': 4.121025    0.306828
  4.119957    0.335473
  4.096208    0.331831
  ...
  0.824808    0.366679
  0.745721    0.586742
  Length: 406, 'Sample2': 3.444444    0.937468
  3.315508    0.855920
  ...
  0.928144    0.236640
  0.918519    0.232346
  Length: 991}
  </code></pre>
  
  <p>This is the code I am using to generate this dictionary, the details of some of it are not relevant, but the spec.Y and spec.X are just numpy arrays:</p>
  
  <pre><code>d = dict()
  for tab in self.tab_list:
      spec = tab.temp_spectra
      name = str(spec.spectra_name)
      d[name] = pd.Series(spec.Y, index=spec.X)
      print(name)
  print(d)
  df = pd.DataFrame(d)
  print(df)
  </code></pre>
  
  <p>Any ideas why this error might be showing up so I can know what to go after to fix?  The column names do not appear to be it, and I was operating under the assumption that the indices can match or not - it shouldn't matter - which is why I am using this package to being with.  I want the 'hashtable' type of feel where the X array can be different or the same and the overlap will put values in the same row or create a new row if needed such that all of it can be viewed together.</p>
  
  <p><strong><em>EDIT:</em></strong> </p>
  
  <p>I figured out the solution had to do with a duplicate entry in the index of one of my datasets (one of my datasets was created on plotly by tracing by hand and therefore got two Y values for one X value).
  I will give a few examples of this in the answer to my own question.</p>