BUG: read_excel with multi-indexed column ignores index_col=None
From SO: http://stackoverflow.com/questions/34020061/excel-to-pandas-dataframe-using-first-column-as-index

@chris-b1 another one on the multi-index excel issues .. :-)

Small test case: content of excel file:

| A | A | B | B |
| --- | --- | --- | --- |
| key | val | key | val |
| 1 | 2 | 3 | 4 |
| 1 | 2 | 3 | 4 |

gives:

```
In [2]: pd.read_excel("test_excel_index_col.xlsx", header=[0,1], index_col=None)
Out[2]:
A     A    B
key val key  val
1     2    3   4
1     2    3   4
```

It's not super clear in the formatting of the dataframe, but the [1, 1] is the index and [A, key] are seen as the level names of the multi-indexed columns.
