This is my profile in Data Explorer. I logged in there with Gmail account which I am using in Stack Exchange. So my user id of any Stack Exchange site is automatically populated there. I have three open id in my Stack Exchange profile. (Gmail, Facebook, and MyOpenId). I don't use Gmail account for login in Stack Exchange (Because I always logged-in in my office with my office's Gmail account). So I use Facebook/MyOpenId for login there. But there is no option to login with Facebook in Data Explorer. So I login with MyOpenId. But it created a new profile there. And there is no option to merge my both open-id (Gmail & MyOpenId) in Data Explorer. While changing openid it shows the following error message:
Another user with this OpenID already exists, merging is not possible at this time.
Why is merging not possible in Data Explorer?