I logged into data.SE today with the same OpenID provider/login I used in the past and found that this time it created a new account rather then logging me into my existing account. Has something happened to the credentials associated with my first account on data.SE?
This should be resolved now. You just have a single account again.
In the past, SEDE hasn't done any variation checking on the openid submitted, so if you logged in with
In fixing this, a bug came up preventing me from finishing the process, so things got into a state where one side of the handshake was dealing with these variations, but the other side wasn't. So, basically, back to square one, oops. All pieces of the puzzle are properly updated now and the couple dupes created during this time have been merged.