Remove duplicate reverse links in users profile

When referencing a user multiple times from a content type, the node is displayed multiple times in the users profile page. Example given: a user is author and lecturer for a submitted paper.

I propose the following change in userreference.module:859:
- $values[$node_type][] = l($node->title, 'node/'. $node->nid);
+ $values[$node_type][$node->nid] = l($node->title, 'node/'. $node->nid);