Duplicate registrations are created if Invitees are imported into the Event manually and then Online Express is used to actually register. This causes the registration fees to be split between them even when fees are manually linked in the Online Express transaction grid to the original one that was imported.
This concern has been resolved with a product release.
Steps to Duplicate
1. Client imports in list of Invitee's to the event using Admin>Import 2. Invited donor uses Online Express event to register and pay for event 3. Client links donor registration to invited donor 4. Client downloads transaction into RE batch 5. Client highlights invited donor in the batch goes to Gift>Apply To>Event>Registration Fees 6. Client links reg fees to original invitee registration 7. Client validates and commits the batch 8. Client goes to constituent record>Events 9. There are 2 registrants (invitee and registrant) and the reg fee is split between them