Today emails sent to me to the mail app on my rmb began showing up as duplicates using the latest mail app and the current version of Yosemite. It's never happened before. I called applecare and they deleted all of Mail and i reinstalled my mail provider, and guess what: same thing is happening. Even odder, it's NOT happening on the same Mail program on the same Yosemite operating system on my 2014 macbook air, and on my 2010 macbook pro. I checked online with my provider and emails are NOT being forwarded in duplicate. Any Mac Sherlocks out there have any ideas? TIA