Scenario:
There can be scenarios where Timesheet is due and Timesheet is overdue notifications have not been enabled in Replicon since the application was set up. After using the application for some time there could be timesheets in due and over-due state. When you enable the Timesheet is due or Timesheet is overdue notification the application would trigger a notification for each of the timesheets that are due or over-due.

Cause:
When the notifications are enabled, the application would check the ReportPeriod table in the database and would trigger a notification for all the timesheets that are due or over-due.

Resolution:
If  you do not want notifications to be sent out for those timesheets you have to either submit or delete those timesheets.