BUG: MultiIndex dtypes incorrect if level names not unique

[johnzangwill]

Pandas version checks

• I have checked that this issue has not already been reported.

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

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

Reproducible Example

import pandas as pd
index = pd.MultiIndex.from_arrays([[1], [2]], names=[1, 1])
index.dtypes
1    int64
dtype: object

Issue Description

If there are duplicate multiIndex levels then dtypes only returns one entry for all the matching levels rather than one for each level

Expected Behavior

import pandas as pd
index = pd.MultiIndex.from_arrays([[1], [2]], names=[1, 1])
index.dtypes
1    int64
1    int64
dtype: object

Installed Versions

INSTALLED VERSIONS

commit : 9093374
python : 3.8.12.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19043
machine : AMD64
processor : Intel64 Family 6 Model 158 Stepping 9, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_United Kingdom.1252

pandas : 1.4.0.dev0+1555.g90933743f2
numpy : 1.21.5
pytz : 2021.3
dateutil : 2.8.2
pip : 21.3.1
setuptools : 60.0.5
Cython : 0.29.26
pytest : 6.2.5
hypothesis : 6.32.1
sphinx : 4.3.2
blosc : None
feather : None
xlsxwriter : 3.0.2
lxml.etree : 4.7.1
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.0.3
IPython : 7.30.1
pandas_datareader: None
bs4 : 4.10.0
bottleneck : 1.3.2
fsspec : 2021.11.0
fastparquet : 0.7.2
gcsfs : 2021.11.0
matplotlib : 3.5.1
numexpr : 2.8.0
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 6.0.1
pyxlsb : None
s3fs : 2021.11.0
scipy : 1.7.3
sqlalchemy : 1.4.29
tables : 3.6.1
tabulate : 0.8.9
xarray : 0.18.2
xlrd : 2.0.1
xlwt : 1.3.0
numba : 0.53.1
zstandard : None

[johnzangwill]

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