This is one area Regent has cut back. Our first cruise was a 19 day total back to back. Rules then were flat $1000 off on a back to back totally 14 days and $1500 off on a back to back longer than 14 days. At that time, it was almost like getting the second trip for very little. Of course, with two 14 day cruises, the 5% probably adds up to more savings but for B2B next year, the back to back discount comes out smaller.