Club lists send multiple emails by accident

I think I have run into the same bug as Thomas Krafft did. I was sending out a save-the-date email to 5 lists who are all being invited to a party. I received the same mail 5 times, all addressed only to the members list. The email was rich text, no attachments. I had no idea this bug existed, until it bit me.

So I have 3 questions:

1. Did Toasthost email all 5 lists 5 times, or only the first list 5 times? I don't want to make the problem worse by trying to fix it...
2. What do I need to do to avoid this bug in future? Just send to 1 list at a time, or is there more?
3. Can the club addresses pop-up change, so that it tells you how to avoid this bug?

Thanks in advance!