A school may have multiple distribution lists created to specify each of their grade levels. For example:
A Grade 1 Distribution List, Grade 2, Grade 3, Grade 4, etc.
These lists each have their own Distribution group associated to them. The school may want to know if publishing a Pushpage to multiple distribution groups containing the same parents will send multiple emails, or just a single email.
Yes, if more than one distribution list is used on a Pushpage it will send an email out multiple times if the user is on more than one list. To avoid this from happening it would be best to create a new Distribution List and Group to ensure that in those circumstances the parent only receives one communication.