Affects Version/s: None
Fix Version/s: 2.0
Though firstname.lastname@example.org, Foo@bar.com and FOO@BAR.com are actually the same thing.
Dashboard currently won't catch that :/
To be more clear, when you add a Secondary Email to your existing account, or use a email to sign-up a new account. Dashboard seems only to ensure this email to be not duplicate with other accounts Primary Emails. So you can add email@example.com, Foo@bar.com and FOO@BAR.com all into your Secondary Email List...
That bug will cause more serious problems.
One user's primary email could be duplicate with the other's secondary email, because sign-up procedure will only ensure the primary email to be unique.
That's to say, this duplicate validate isn't mutual.
So, user A first add firstname.lastname@example.org as one of his secondary email, then user B use email@example.com to sign-up one account.
Now user A will have one unremovable secondary email firstname.lastname@example.org, and he can never add any other secondary emails. That's terrible.