There can be a few reasons you are receiving multiple service emails.
1) You will receive a service notification if you are selected as a service contact on the case to receive service. If receiving multiple notifications, check to see how many times you are on the service contact list. If you are listed/selected multiple times, you will get multiple emails. You only need to be on the service list once to receive service.
2) Each filing in a served envelope gets it own notification of service email. If someone files multiple filings in one service envelope, then you will receive an email for each service/lead document selected for service in the envelope.
3) As an administrative copy for a service contact, you will receive an email notification when the service contact is selected for service. Check to see if you are added as an administrative copy to a service contact in the case.