Defender for cloud sending multiple emails, one for the built in roles and another for the others

in the email notifications section of defender for cloud, you can select, owners, AccountAdmin, ServiceAdmin and contributor, then there is another line for additional email addresses (separated by commas), when an alert hits, it is sending out one email for the owners and another email for the additional email list.  is this a normal thing?  it is making communication between the 2 groups really painful.