title: Can't create same id another model
body: <p>I'm developing Ruby 1.8.7 and Rails 2.3.8.
  I'm trying to create same id another model in an action.</p>
  
  <pre><code>def create
    id = params[:id]
    item_master = ItemMaster.new(params[:item_master)
    item_master.id = id
    item_master.save
    item_master_child = ItemMaster.new(params[:item_master_child])
    item_master_child.id = id
    item_master_child.save
    p item_master
    # =&gt; ItemMaster id: 654, style: 6, icon: 7
    p item_master_child
    # =&gt; ItemMasterChild id: 654, sub_style: 4, roll: 5
  end
  </code></pre>
  
  <p>It seems that save finished successfully, but actually item_master params becomes id: 654, style: 0, icon :0. All params except id becomes 0.
  Any ideas?</p>