Dorico margin & PDF margins differ.(Solved)

Page size is 9x12
I have the default left/right margins set (42pt or a little more than 1/2in). When I print to PDF, the margins area are (81pt or a little over an inch.

Looks like, when creating booklet(12x18)-two 9x12", I set page for PDF size at 12x18. I should have set it at 9x12 then print from DPF using 12x18 booklet. The resulting margins come out correct.