[Hall of Famer]

Actually it's not that easy, the password hashing/encryption system uses both username and password(plus other things like pepper and salt). Simply changing username in database will not suffice, as you will still end up with errors telling you that the password is incorrect. However, you may try resetting password with the second account, you should receive password reset emails without problems if your email is valid and correct.

If you know the pepper and salt code, you can manually execute the password encryption function to get the 128-characters password hash. Its very easy for me but cant say the same for beginners. Thats why I said you might want to PM me for a much more detailed explanation/tutorial on how to do that, if you desperately wish to go through this procedure.