My Assistant is sending duplicate emails

Weekly, after Payroll Posts, I send Job Cost reports out to the Project Managers via MA.  Recently, I have added a few Superintendents to the "To" line in the email distribution.  I use the email directory for Superintendents that looks to the Job Setup for this information.  Since I started this, the Project manager now receives the email twice.  How can I stop the duplicates?

TIA,

Leslie