Notifications not sent: Custom notification with multiple node-type conditions only has one in notifications_fields

To reproduce, create a custom notification with multiple fields conditions for "node-type" (in my case, node-type = blog and node-type = forum). Subscribe a user to the notification, (this triggers the creation of the notification in tables notifications and notifications_fields). Then check notifications_fields for records relating to the notification ID.

Only one record is present, for the last condition. In the above example, I have a record for (node-type = forum), but not for (node-type = blog). Thus new blog posts will never trigger a notification.

My expected behavior would be to have multiple records in notifications_fields, one for each node-type condition defined in the Custom admin page.

It occurs to me that this may be by design, and the fields functionality could be intended for increasingly-specific filtering, not aggregation of multiple node types. If so, the UI should probably be changed to only allow one instance of a "node-type" field condition to be assigned for a custom notification.