My email lists seem to be sending out the monthly reminder twice to each user. Is there a simple way to understand why this is happening and how to fix it?

I've checked the crontab entry and it looks like this: # 5 AM on the first of each month, mail out password reminders. 0 5 1 * * /usr/local/bin/python -S /home/mailman/cron/mailpasswds

and there are no duplicates.

I'm sure someone has seen this before??