Just got off the phone and figured I'd share here in case others are seeing the same thing. I have a set amount auto-invested on the first of every month, but today I noticed that my checking account had been pinged twice for that amount, one of which was still pending.
I called Vanguard immediately and while they were transparent that there is a systems error causing the multiple/duplicate contributions, they were not able to give a concrete date of resolution. The agent said that a fix is "in motion" and that any erroneous contributions should be reversed by EOD, but that some customers may have to wait until EOW to get things reversed.
I get that things happen, but I'm hoping no one has to wait until EOW for this to sort itself out. It wasn't a great feeling to wake up and see $$$$ less in my checking account than I anticipated, especially when all of my bills are on autopay.