OK, so this is really interesting. I have two email accounts on my phone... my personal account and my work account. With iOS 8.0 I was getting double notifications on the work account, but not my personal account. So, after I installed iOS 8.0.2 I tested with a few emails to my work account and I didn't seem to be getting any double notifications, so I posted above and said that I thought the problem was resolved.
Even through this morning I've been getting emails to my work account with no double vibrations, so I was quite happy. But just a few minutes ago I got an email on my personal account and it did the whole double notification thing🙁
So, it appears that it might be an account specific issue, or perhaps something that happens to one account when you have two email accounts on the phone (I wonder if you had three email accounts if you would get a triple notification for one).
For you guys who are experiencing this issue, do you have more than one email account enabled? And if so, does it only happen to one account?