I just got an email that said it was just autrorised on a second conputer but I only have it installed on one.
 
This is the included essentials version.
 
Has anyone else seen this?

Yes, I had the same thing happen to me (except it was for the full version, Melodyne editor).
 
I emailed Celemony and will report back here when I receive a reply.  I should mention that I tried a few days ago but my message was bounced back to me as undeliverable.  I checked the address (registration AT celemony DOT com), and it was correct, so I'm not sure why it didn't go through.  Maybe it was Cyber Monday-related.  :-)
 
Cheers...