Im having the same problem! I can register several users with same email!?? I created a standard SA wizard set without modifications. Fresh DW install, fresh extensions install, all cleared before building the standard pages! Of course one could set email field in db as unique but the server validation behaviour should take care of that check!? I have tried manually editing the WA server validations in the registration page but nothing can be changed in that dialog!? If I delete a value and try to reapply it nothing changes! There is a validation typ "unique database value" which I tried to apply on the email field in addition to the "Email address" validation type but it does not work!?