"Log in through wordpress.com" logs in wrong user
If you log into your site using the "log in through wordpress.com" button and find that you are logged in as a different user, this is likely caused by Jetpack being confused. :)
You should be able to resolve this by disconnecting the incorrect user from Jetpack, and then logging in as normal.
How to resolve
1. Log in to your WordPress.com account. Head to My Sites. There, you'll see a list of all your blogs and connected sites.
2. Find the correct site in the list.
3. Scroll down to "settings" and click to open.
4. Click "disconnect from WordPress.com" (it's red).
5. Try logging in to your site again using the "log in through wordpress.com" option.