ctools_object_cache_get() returns reference, instead of clone

I'm not sure if the following issue is the expected behaviour, but I had some code affected by that which prevented the right node submission (throwing some errors: #1627860: Unable to add new content with empty upgraded image/file field #6 and doing some really really weird stuff).

Following simple code is explaining the problem:

  $node_in = new stdClass(); // We create a new node object
  $node_in->type = 'page'; // We set content type
  ctools_object_cache_set('test', 'node', $node_in);
  $test = ctools_object_cache_get('test', 'node');
  $test->type = 'overridden';
  $node_out = ctools_object_cache_get('test', 'node');
  var_dump($node_out); exit;

returns:

string(9) "overridden"

drush version:

$ drush eval "$node_in = new stdClass(); $node_in->type = 'page'; ctools_object_cache_set('test', 'node', $node_in); $test = ctools_object_cache_get('test', 'node'); $test->type = 'overridden'; $node_out = ctools_object_cache_get('test', 'node'); var_dump($node_out); exit;"
Drush command terminated abnormally due to an unrecoverable error.                                                                                                                             [error]
object(stdClass)#230 (1) {
  ["type"]=>
  string(9) "overridden"
}

It seems that once variable is cached by CTools, the value/structure can be overridden using some local function.
In my case the function which was overriding my cached object was _field_invoke_multiple() when doing node preview in my multistep form.
See: #1622952: The right way to programatically render the preview of node object before the creation #3
More details about my problem:
http://drupal.org/node/1627860#comment-6204076

Following code can solve the problem when getting the cached object:

  $test = clone ctools_object_cache_get('test', 'node');

or to clone returning object in ctools_object_cache_get()