Attendee registration form settings lost in original event when save cloned event

[viklik]

I create event_original, configure attendee registration form there and save this event. When event is successfully created, I click on duplicate icon to create event_copy. This event_copy has the same registration form settings as event_original.

When I edit and save event_copy, in event_original attendee registration form settings are lost and showing "undefined". This make event registration unusable.

Please fix. Thank you.