It appears that the notifications package was mounted twice. It's not meant to be multiply-mounted, and the code assumes this. Since you can't delete a site node from the site-map you have to do it through psql or just drop your db. Here's the sql if you want to do it that way:
1. select *, site_node__url(node_id) from site_nodes where object_id = (select package_id from apm_packages where package_key = 'notifications');
2. pick the node_id that's where url is not equal to /notifications/
3. then delete it with:
delete from site_nodes where node_id = XXXX;
or just drop the db, since there could be side-effects to this that I don't know about.
