With the register snippet, Person #1 can register using a certain username and get the activation email. When Person #2 registers using the same username but a different email address within Person #1's activation ttl (3 hrs), the user is overwritten with Person #2's data and Person #1's activation link becomes invalid.
Is there a way to prevent this case by not allowing Person #2 to register with a username of an inactive account that has not expired yet?