ruby include method name collision

If a class includes many modules, and the methods gained from the include call private methods from their originating modules, and private methods exist in other modules with the same name, it should use the definition from its own module. In code:

module C
  def c
    puts collision
  end
  private
  def collision
    'c'
  end
end
module B
  def b
    puts collision
  end
  private
  def collision
    'b'
  end
end
class A
  include B
  include C
end
A.new.b
# => 'c'

I expected A.new.b to give 'b' and A.new.c to give 'c' but there is collision because they use the same private method name. In large projects with many includes, how is this avoided?