Do you have Filter,Escalation logs when these transactions where performed.This will help in further Investigation
This table is updated as it contains information about a historical notification sent and it contains a LoginID that needs to be altered to maintain data integrity
(This data is exposed in places like the Incident, where one can open up the audit log and see this table of data with all the notifications sent)
as a good practice you can either delete or archive data from this form. After few years i don't think this data is much needed if HPD:Helpdesk data is already archived.