Ok – it looks like there’s a fix for this (glad it’s an easy one):
Go to your Contact form admin page – at the top, there are now two snippets of code – a new snippet and an old snippet. Chances are your page is still using the old snippet. When I copied the new snippet, pasted it into my contact page, and tested a submission, I received only one notification email.
Hope this helps anyone else facing the same issue. Chaos, let us know if it worked for you!
I started experiencing this upon upgrade too. I am still on WP 3.2.1 The Plugin said there was 100% compatibility with this version, so I updated. Is there any way to revert back to the previous version of Contact Form 7, or fix this issue?