If the Service Contacts list on one envelope in a given case differs from the Service Contacts list on another envelope from the same case, this is typically because the case was moved from one court to another.
When this occurs, the moved case is treated as an entirely different case. Because of this, certain changes may occur in the case details, including the case's Service Contacts list.
If this has occurred to your case, you may need to re-add specific Service Contacts to your case's Service Contacts list.