code: def test_columns_with_dups(self):
      # GH 3468 related
  
      # basic
      df = DataFrame([[1, 2]], columns=["a", "a"])
      df.columns = ["a", "a.1"]
      expected = DataFrame([[1, 2]], columns=["a", "a.1"])
      tm.assert_frame_equal(df, expected)
  
      df = DataFrame([[1, 2, 3]], columns=["b", "a", "a"])
      df.columns = ["b", "a", "a.1"]
      expected = DataFrame([[1, 2, 3]], columns=["b", "a", "a.1"])
      tm.assert_frame_equal(df, expected)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Series, date_range
  import pandas._testing
label_desc: Use image node_id 10 for calling the TestDataFrameNonuniqueIndexes obj's underlying member method code with example usage: obj.test_columns_with_dups() without return types