Does my Mint email and password have to be the same as my Mint Account Center email and password?
No. The Mint Account Center and your individual Mint installations are completely separate, independent systems.
To retrieve your Mint Account Center password please visit the password reminder form. If you do not remember the email address used when creating this account be sure to mention one of your licensed domains when you email for assistance.
To retrieve your Mint installation password please see this FAQ.