[Plugin: Add Multiple Users for WordPress] Forcing Add Users Without Emails

When I try to add users without an email, I get an error that says “1. Error:: The email address entered <> for the user already exists. Please try adding this user again with a unique email”.

I am checking the box that says “Force fill empty email addresses”

Is anyone else seeing this error?

http://wordpress.org/extend/plugins/add-multiple-users/