I had the same issue early on, and usually if someone asked I'd explain about it being more cost effective to send as two packages due to the size etc, but gave a 50c discount on the total anyway because 1 payment for two items = 1 less PayPal flagfall. (I always said something along the lines of savings would be minimal due to it being more cost effective to send two packages, but I'll provide the discount as a thank you / courtesy for the multiple purchase - was always thanked kindly. 🙂 )