The benefit is OBC. I THINK it is between $50 - $200 depending on the lengh of the cruise.
The OBC for booking a seven day cruise is $100.
You also get two certs. for friends or family to recieve the same OBC IF they book the SAME cruise you booked.
I believe they have to book within 60 days of you booking.
I THINK you would need to cancle your current booking for the second cruise before you sail on the first cruise.
The promotion is only valid on new bookings. When booking on board the full deposit must be paid then. If you cancle the
second booking I THINK you will have to pay the deposit for the new booking and Carnival will refund at a later date the deposit
you paid when you originally booked the second cruise.
OK - I think that is explained clearly - about as clear as mud!!! Sorry, hope it makes sence.