Description of the problem:

Only most recent mta notification is displayed in notifications table.

When running the MTA workflow with the same inputs over and over again only 1 notifications shows up in the table. Same thing happens for m2k notifications. 

How reproducible:

100%

Steps to reproduce:

1. run MTA or M2K workflow with same inputs multiple times

2. Check notifications table and observe that only the most recent notification is in the table

Actual results:

Only most recent notifications is displayed in the table, also the notification count in the API isn't correct

Expected results:

All notifications should be displayed in the notifications table