Ruby Forum Ruby on Rails > ActiveRecord handling of obj.dup vs obj.clone

AR seems to be handling model object dup and cloning differently from
Ruby documented behavior.  I've checked out both ways (as an AR model
and not) and the behavior is different.  I don't see anything in the
RAILS documentation about this.  Am I missing something? is this a bug?
a feature? an interesting lifestyle?
I can easily hack around this difference/bug/feature but it should be
unnecessary.
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example 1 using AR:

class Model < ActiveRecord::Base
# etc, normal model stuff, associations
  def initialize_copy(old_obj)
    # do something
  end
end

obj = Model.find(1)
obj_dup = obj.dup   # does NOT yield a new object;
                    # does invoke obj_dup.initialize_copy(obj)
# at this point obj_dup is same object as obj;
# any changes to obj_dup will change obj
# but obj_dup changes have not been saved to DB yet

obj_clone = obj.clone  # does yield a new object;
                       # does NOT invoke obj_clone.initialize_copy(obj)
# at this point obj_clone is a different object but not yet saved to DB
# which is ok and expected; NOT invoking initialize_copy is NOT ok
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example 2 using pure Ruby:

class Test
   attr_reader  :name
   def initialize(str)
     @name = str
   end
   def initialize_copy(old)
      @name += ' *** COPY ***'
   end
end

a = Test.new 'john'   # a.name is now: 'john'
b = a.dup    # b.name is now: 'john *** COPY ***'
c = a.clone  # c.name is now: 'john *** COPY ***'

# a, b, c are all DIFFERENT objects
# b.initialize_copy(a) was invoked per Ruby documentation #
c.initialize_copy(a) was invoked per Ruby documentation