[BUG-REPORT] cannot request duplicate column names before export to arrow or parquet

[Ben-Epstein]

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Description Please provide a clear and concise description of the problem. This should contain all the steps needed to reproduce the problem. A minimal code example that exposes the problem is very appreciated.

Software information

• Vaex version (import vaex; vaex.__version__): 4.12.10
• Vaex was installed via: pip / conda-forge / from source pip
• OS: Mac/Linux

Additional information

import vaex

df = vaex.example()

cols =  ["x","x","y","z","y"]
df = df[cols]
df.export("file.arrow")  # fails
df.export("file.parquet")  # fails
df.export("file.csv")  # works

import vaex

df = vaex.example()

cols =  ["x","x","y","z","y"]
df = df[list(set(cols))]
df.export("file.arrow")  # works
df.export("file.parquet")  # works