FEATURE: allow staff to send multiple invites to same email

app/controllers/invites_controller.rb

@@ -35,6 +35,11 @@ class InvitesController < ApplicationController
 
     guardian.ensure_can_invite_to_forum!(group_ids)
 
+    invite_exists = Invite.where(email: params[:email], invited_by_id: current_user.id).first
+    if invite_exists
+      guardian.ensure_can_send_multiple_invites!(current_user)
+    end
+
     if Invite.invite_by_email(params[:email], current_user, topic=nil,  group_ids)
       render json: success_json
     else