There seems to be no rhyme or reason to this, but there will be periods where someone will respond to a thread I'm following and I'll get two emails, immediately after one another, that are identical.

This isn't two people posting to the topic near the same time, this is one specific email on a topic that is being sent.  The really odd thing is that I don't think this happens with every notification.  However, when it does occur, it tends to happen with every notification for short period of time.  I've not timed it but it's probably on the order of a couple hours.

This is a bizarre bug, but I thought I'd mention it in case it's eating up any server resources.  Might be worth looking into.  Oh, and I don't think I'm getting duplicate messages in my NA inbox.  I'm just getting dupe emails to my personal email address.

I'm not getting any notification emails. Haven't for years now. Just stopped working for me.