code: def test_fillna_dict_inplace_nonunique_columns(
      self, using_copy_on_write, warn_copy_on_write
  ):
      df = DataFrame(
          {
              "A": [np.nan] * 3,
              "B": [NaT, Timestamp(1), NaT],
              "C": [np.nan, "foo", 2],
          }
      )
      df.columns = ["A", "A", "A"]
      orig = df[:]
  
      # TODO(CoW-warn) better warning message
      with tm.assert_cow_warning(warn_copy_on_write):
          df.fillna({"A": 2}, inplace=True)
      # The first and third columns can be set inplace, while the second cannot.
  
      expected = DataFrame(
          {
              "A": [2.0] * 3,
              "B": [2, Timestamp(1), 2],
              "C": [2, "foo", 2],
          }
      )
      expected.columns = ["A", "A", "A"]
      tm.assert_frame_equal(df, expected)
  
      # TODO: what's the expected/desired behavior with CoW?
      if not using_copy_on_write:
          assert tm.shares_memory(df.iloc[:, 0], orig.iloc[:, 0])
      assert not tm.shares_memory(df.iloc[:, 1], orig.iloc[:, 1])
      if not using_copy_on_write:
          assert tm.shares_memory(df.iloc[:, 2], orig.iloc[:, 2])
  
imports: import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  from pandas import Categorical, DataFrame, DatetimeIndex, NaT, PeriodIndex, Series, TimedeltaIndex, Timestamp, date_range, to_datetime
  import pandas._testing
  from pandas.tests.frame.common import _check_mixed_float
label_desc: Use image node_id 1 for calling the TestFillNA obj's underlying member method code with example usage: obj.test_fillna_dict_inplace_nonunique_columns(using_copy_on_write, warn_copy_on_write) without return types