This is on a multisite install, but not turned on as a network plugin. After a complaint from a client, I tried it on my testing site, with no other non-mu plugins.
I keep getting
Duplicated username or email address.
. I know it used to work, because I have 2 email addresses that have two users each. So either it's interacting badly with a mu-plugin or 2.0.1 broke things. I am *not* looking forward to testing against mu-plugins!