I did this in the past. Aparently I forgot I had an account, setup a new one, then found my older account, after some email migrations, they ended up on the same email with the same password. I think it was pretty consistent about which account I logged into, but changing the email (or the password, I guess) of that account let me access the otherwise hidden account. They still have no merge feature, but at least they let you change your email address, unlike some sites.