Duplicated column name causes inconsistent ValueError during assignment to a unique column
#### Code Sample, a copy-pastable example if possible

```python
df1 = pd.DataFrame([[1,2,3,4]], columns=['C','D','D','a'])
df1['a'] = df1['a']

ValueError: Buffer has wrong number of dimensions (expected 1, got 0)
```
However, the following works without an error message:
```python
df1 = pd.DataFrame([[1,2,3,4]], columns=['C','B','B','a'])
df1['a'] = df1['a']
```
#### Problem description
I believe ValueError should not be thrown in the first example. The issue appears to only occur when there is a duplicated column. Interestingly, there appears to be some link to the alphabetical order of the column names. 

This appears similar to the issue reported in [#21668](https://github.com/pandas-dev/pandas/issues/21668).

#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.7.0.final.0
python-bits: 64
OS: Linux
OS-release: 4.14.76-1-lts
machine: x86_64
processor: 
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.23.4
pytest: None
pip: 18.0
setuptools: 40.4.3
Cython: None
numpy: 1.15.2
scipy: 1.1.0
pyarrow: None
xarray: None
IPython: 6.5.0
sphinx: 1.8.0
patsy: 0.5.0
dateutil: 2.7.3
pytz: 2018.5
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 2.2.3
openpyxl: 2.5.7
xlrd: 1.1.0
xlwt: None
xlsxwriter: None
lxml: 4.2.5
bs4: None
html5lib: 1.0.1
sqlalchemy: 1.2.12
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

</details>
