Duplicate email notifications for iCloud calendar events?

So any time someone adds an event to a shared iCloud calendar, I have it set (in my calendar “advanced” prefs on iCloud.com) to send me an email notification - but every single time, I receive TWO identical emails. Any thoughts on how to prevent this?

Both emails look like this and have the same time stamp.

I saw that one time when I had a shared calendar that I created with my iCloud account and also participated in from a different email account, along with the other participants. In other words, I was a participant twice.