Blackout notifications are displayed twice based on start/end dates

[lauratomas]

Notifications for both soft and hard blackouts are displayed twice if start and end dates for a reservation fall within the blackout range.

For example, a hard blackout with notification was created for July 15 - July 18. While on the catalog view, setting the start date to July 15 and the end date to July 17 triggered two identical notifications. Edited the blackout to a soft blackout and saw the same duplicate notifications.

Setting the start date to July 14 and end date to July 17 only the notification once.