Birthday Email is Sent Multiple Times

I've set up an automated Birthday Email campaign following the instructions for two smart campaigns provided by the Sending a Birthday Message post. Both smart campaigns are set so each person can only run through the campaigns once every 364 days. However, on the person's birthday, the birthday email is sent to each person multiple times until the communication limit is reached. Why is this email being sent multiple times?

Batch Campaign

Notes: 1/1/1900 is sometimes used as a default date if DOB is empty. The countries are limited to only North & South America for time zone reasons. 

Trigger Campaign (inactive until I resolve the issue)