STEPS TO REPRODUCE:
1) Create a SRD which generated an approval.
2) Go to people profile of an approver and then Notifications tab
3) Click on Update Notification Preferences and create a new entry
Module Name : Request Management
Notification Event : Approval
Set no to all the notification method and other fields.
4) Create a new request with this SRD where approval is generated to this user
The user is getting approval notification
The user should not get approval notification
You need to make use of sort order field if you are creating more than one record for Module Name and Notification Event combination.