jorisvandenbossche opened a new issue, #46179:
URL: https://github.com/apache/arrow/issues/46179

   ### Describe the bug, including details regarding any error messages, 
version, and platform.
   
   The pandas -> arrow conversion adds a `__inex_level_i__` column if the 
dataframe has an unnamed it wants to preserve (i.e. if it is not just a pandas 
RangeIndex). But if your dataframe already has such a column, you end up with a 
duplicate field:
   
   ```
   In [40]: df = pd.DataFrame({"col": [1, 2, 3], "__index_level_0__": [1, 2, 
3]}, index=[2, 3, 4])
   
   In [41]: df
   Out[41]: 
      col  __index_level_0__
   2    1                  1
   3    2                  2
   4    3                  3
   
   In [42]: pa.table(df)
   Out[42]: 
   pyarrow.Table
   col: int64
   __index_level_0__: int64
   __index_level_0__: int64
   ----
   col: [[1,2,3]]
   __index_level_0__: [[1,2,3]]
   __index_level_0__: [[2,3,4]]
   ```
   
   We could have it bump the integer number in the generated column? (although 
we would have to check how that works in the full roundtrip then)
   
   ### Component(s)
   
   Python


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