Consider:

==================================================================================
-->from enum import Enum

-->class Color(Enum):
...   red = 1
...   green = 2
...   blue = 3
...   red = 4
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 5, in Color
  File "/home/ethan/source/python/issue18924/Lib/enum.py", line 87, in __setitem__
    raise TypeError('Attempted to reuse key: %r' % key)
TypeError: Attempted to reuse key: 'red'
==================================================================================

versus

==================================================================================
-->class Color(Enum):
...   red = 1
...   green = 2
...   blue = 3
...   def red(self):
...     return 'fooled ya!'
... 

# no error
==================================================================================

or

==================================================================================
-->class Color(Enum):
...   red = 1
...   green = 2
...   blue = 3
...   @property
...   def red(self):
...     return 'fooled ya!'
... 

# no error
==================================================================================

In both of the latter two cases the redefinition of 'red' is allowed because the new definition is not an enum member.

This is inconsistent as well as confusing.

I know normal class creation semantics don't place any such limitations on names and allow redefining at will, but Enum is not a regular class.