BUG: Raname a column to have the same name to other column creates a DataFrame with two columns with the same name

[fedegr]

Pandas version checks

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• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

df = pd.DataFrame({"a":[1], "b":[2]})
df.rename(columns={"b": "a"})
#    a  a
# 0  1  2

Issue Description

Renaming a column to have a name of another column generates a new DataFrame with 2 columns with the same name

Expected Behavior

I would expect an error or the old column to be replaced.

Installed Versions

Matplotlib created a temporary config/cache directory at /tmp/matplotlib-sqyn173n because the default path (/config/matplotlib) is not a writable directory; it is highly recommended to set the MPLCONFIGDIR environment variable to a writable directory, in particular to speed up the import of Matplotlib and to better support multiprocessing.

INSTALLED VERSIONS
------------------
commit           : 66e3805b8cabe977f40c05259cc3fcf7ead5687d
python           : 3.8.12.final.0
python-bits      : 64
OS               : Linux
OS-release       : 5.11.0-1026-gcp
Version          : #29~20.04.1-Ubuntu SMP Fri Jan 7 12:24:31 UTC 2022
machine          : x86_64
processor        : 
byteorder        : little
LC_ALL           : en_US.UTF-8
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.3.5
numpy            : 1.22.1
pytz             : 2021.3
dateutil         : 2.8.2
pip              : 21.2.dev0
setuptools       : 56.0.0
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : 1.1
pymysql          : None
psycopg2         : None
jinja2           : 3.0.1
IPython          : None
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : 3.4.3
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyxlsb           : None
s3fs             : None
scipy            : 1.4.1
sqlalchemy       : 1.4.23
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : None

[phofl]

This behaves as expected, duplicated column names are valid.