I have the same issue as well, with pretty much duplicate messages in the morning and evening (presently at 1 AM and 7 PM ET as mentioned in the first post), though the messages (even within one subscription) are not actually identical. Going through my email history, it appears I began getting the extra messages in the evening (before then they always only arrived at 1 AM ET) on 10/9/2012.
Not too big a deal, but it would be nice to not be getting 'near'-duplicate messages twice a day.
If it's any help to the admins who might ever look at the issue, I save pretty much all of my email, so I have all the countless duplicate messages, if they may be of any use to anyone.
Thanks,
McCoy