Strange "reindexing error" converting Series to DataFrame - python-3.x

Question

I have two Series objects, which from my perspective look exactly the same, except they contain different data. I have attempted to convert them to DataFrames and to put them both in the same DataFrame as separate columns. For some reason I cannot fathom, one of the Series will be converted happily to a DataFrame and the other one refuses to be converted when placed in a container (list or dict). I get a reindexing error, but there are no duplicates in the index of either Series.
import pickle
import pandas as pd
s1 = pickle.load(open('s1.p', 'rb'))
s2 = pickle.load(open('s2.p', 'rb'))
print(s1.head(10))
print(s2.head(10))
pd.DataFrame(s1) # <--- works fine
pd.DataFrame(s2) # <--- works fine
pd.DataFrame([s1]) # <--- works fine
# pd.DataFrame([s2]) # <--- doesn't work
# pd.DataFrame([s1, s2]) # <--- doesn't work
pd.DataFrame({s1.name: s1}) # <--- works fine
pd.DataFrame({s2.name: s2}) # <--- works fine
pd.DataFrame({s1.name: s1, s2.name: s1}) # <--- works fine
# pd.DataFrame({s1.name: s1, s2.name: s2}) # <--- doesn't work
Here is the output, although you can't see it here, there is overlap between the index values; they are just in a different order. I want the indexes to be matched when I combine them into the same DataFrame.
id
801120 42.01
801138 50.18
801139 50.01
802101 53.77
802110 56.52
802112 47.37
802113 46.52
802114 46.58
802115 42.59
802117 40.85
Name: age, dtype: float64
id
A32067 0.39083
A32195 0.28506
A01685 0.36432
A11124 0.55649
A32020 0.41524
A32021 0.43788
A32098 0.49206
A00699 0.37515
A32158 0.58793
A14139 0.47413
Name: lh_vtx_000001, dtype: float64
Traceback when the final line is uncommented:
Traceback (most recent call last):
File "/Users/sm2286/Documents/Vertex/test.py", line 18, in <module>
pd.DataFrame({s1.name: s1, s2.name: s2}) # <--- doesn't work
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 224, in __init__
mgr = self._init_dict(data, index, columns, dtype=dtype)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 360, in _init_dict
return _arrays_to_mgr(arrays, data_names, index, columns, dtype=dtype)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 5236, in _arrays_to_mgr
arrays = _homogenize(arrays, index, dtype)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 5534, in _homogenize
v = v.reindex(index, copy=False)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/series.py", line 2287, in reindex
return super(Series, self).reindex(index=index, **kwargs)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/generic.py", line 2229, in reindex
fill_value, copy).__finalize__(self)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/generic.py", line 2247, in _reindex_axes
copy=copy, allow_dups=False)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/generic.py", line 2341, in _reindex_with_indexers
copy=copy)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/internals.py", line 3586, in reindex_indexer
self.axes[axis]._can_reindex(indexer)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/indexes/base.py", line 2293, in _can_reindex
raise ValueError("cannot reindex from a duplicate axis")
ValueError: cannot reindex from a duplicate axis
Traceback when line 13 is uncommented:
Traceback (most recent call last):
File "/Users/sm2286/Documents/Vertex/test.py", line 13, in <module>
pd.DataFrame([s2]) # <--- doesn't work
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 263, in __init__
arrays, columns = _to_arrays(data, columns, dtype=dtype)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 5359, in _to_arrays
dtype=dtype)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/core/frame.py", line 5453, in _list_of_series_to_arrays
indexer = indexer_cache[id(index)] = index.get_indexer(columns)
File "/Users/sm2286/anaconda3/lib/python3.5/site-packages/pandas/indexes/base.py", line 2082, in get_indexer
raise InvalidIndexError('Reindexing only valid with uniquely'
pandas.indexes.base.InvalidIndexError: Reindexing only valid with uniquely valued Index objects

Answer 1

After more investigation the difference between the Series was that the latter contained missing values. Removing them fixed the issue.