I can only guess that the Account.equals() method in Windows' codebase looks like this:
return this.emailAddress == account.emailAddress;

A while back, I realized I no longer needed my Hotmail address, and set up my Microsoft account to use my G-mail address. This simplified things quite a lot for me. This is the account I use to log into Windows 8.
I just decided to try out the much-hated Mail app, and set up my G-mail account there. After some imperfectness, I thought about just removing it and using Chrome G-mail on its own. However, I ran into this:

Click image for larger version
They seem to falsely think that my G-mail account is the same as my Microsoft account, when in reality there's no reason I shouldn't be able to remove this. (Heck, it wasn't there 10 minutes ago) Any ideas? If this is a real bug, any way to submit it to Microsoft?