CFLIDPA

Is there a way to limit shooters to only signing up once for any given match? In some games they can register multiple times to shoot the match with multiple guns, but in IDPA that isn't allowed. Is there something I can do in the registration form set-up that will prohibit an email address from registering if they've already registered using that email address? Current process is to manually delete duplicates, but with larger matches the duplicates might get missed.