How to allow same email to different member in Umbraco

How to allow same email to different member/user in Umbraco


Environment
- Umbraco version 7.6.3 assembly: 1.0.6361.21154
- VS2015

Add

requiresUniqueEmail="false"

to web.config like below:

<membership defaultProvider="UmbracoMembershipProvider" userIsOnlineTimeWindow="15">
      <providers>
        <clear />
        <add name="UmbracoMembershipProvider" type="Umbraco.Web.Security.Providers.MembersMembershipProvider, Umbraco" minRequiredNonalphanumericCharacters="0" minRequiredPasswordLength="10" useLegacyEncoding="false" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" defaultMemberTypeAlias="Member" passwordFormat="Hashed" allowManuallyChangingPassword="false"  requiresUniqueEmail="false" />
        <add name="UsersMembershipProvider" type="Umbraco.Web.Security.Providers.UsersMembershipProvider, Umbraco" minRequiredNonalphanumericCharacters="0" minRequiredPasswordLength="10" useLegacyEncoding="false" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" passwordFormat="Hashed" allowManuallyChangingPassword="false" />
      </providers>
    </membership>