title: Knockout copying observable array issue
body: <p>I am trying to copy one observably array to another observable array.  I have a form that has a billing address, shipping address and checkbox that when clicked allows the user to copy all of their shipping info to their billing address.  The problem I am having is when I copy one observable array to another, then any time I make a change to either observable both observable arrays get updated.  I would like to keep both observable array values seperate just copy the values from one to the other.</p>
  
  <p>My observable arrays are set up using the <a href="http://knockoutjs.com/documentation/plugins-mapping.html" rel="nofollow noreferrer" title="mapping plugin">mapping plugin</a>:</p>
  
  <pre><code>self.billingAddress = ko.mapping.fromJS(InitialEmptyAddressModel);
  self.shippingAddress = ko.mapping.fromJS(InitialEmptyAddressModel);
  </code></pre>
  
  <p>Then to copy shipping info to billing after entering shipping information and clicking on 'Use Shipping Address':</p>
  
  <pre><code> self.CopyAddress = function() {
      self.billingAddress(self.shippingAddress());
      }
  </code></pre>
  
  <p>I've also tried the following:
  <a href="https://stackoverflow.com/questions/6509297/what-is-the-best-way-of-cloning-copying-an-observablearray-in-knockoutjs">What is the best way of cloning/copying an observablearray in knockoutJS?</a></p>
  
  <p>Any help would be appreciated thank you.</p>