Breadcrumb doesn't work when classes have the same construct values

My configuration described here: #924132: Override and order of taxonomy plugin
I've disabled taxonomy plugin, enabled mine (taxinav),
My class looks like:

class taxinav_class_CrumbsParentFinder {

  function construct() {
    return array(
      'admin' => new self,
      'hierarchy' => new _taxinav_CrumbsParentFinder__hierarchy,
      'term_node' => new _taxinav_CrumbsParentFinder__term_node,
      'term_name' => new _taxinav_CrumbsParentFinder__term_name,
    );
  }
...

In this case breadcrumb doesn't work, because names of the keys like 'admin', 'hierarchy', etc. already exists in other plugin ('admin' is quite common name). Doesn't matter if it's disabled.

Changing to:

      'taxinav_admin' => new self,
      'taxinav_hierarchy' => new _taxinav_CrumbsParentFinder__hierarchy,
      'taxinav_term_node' => new _taxinav_CrumbsParentFinder__term_node,
      'taxinav_term_name' => new _taxinav_CrumbsParentFinder__term_name,

does work.

Probably the bug is somewhere in following code (crumbs.PluginEngine.inc)

      foreach ($objects as $instance_key => $object) {
        $instanceBasket->addPluginInstance($instance_key, $object);
      }