Employees reported they were notified about reminders that were already acknowledged by them

[newtonbeck]

Steps to reproduce the bug

1. Create a simple non-recurrent reminder;
2. Acknowledge the reminder;
3. The employees are notified by email even after they have already acknowledged the reminder;

Expected behavior

Acknowledged reminders should not be sent by email to employees;

Current behavior

All reminders are being sent by email to employees;