Users unable to register an account using the same email address.

Hello,

I need to be able to allow users to register new accounts using the same email for different stores. For instance, if customerA has an account on store1 and creates another account on store1, customerA will need to use a new email address that customerA is not already using. If customerA has an account on just store1 and not store2 and registers a new account on store2, then the same address can be used.

I've tried overriding the current login method with a plugin I wrote, however due to how the cookie is generated I'm unable to get it to work without causing logins to fail completely.

I can provide more information if needed.

Thanks!