Are you one nuclear family with 2 rooms or extended family/friends with 2 rooms. If you are one nuclear family (ie: mom in one with a kid and dad in the other with another kid) you only buy one package and then on the first day you go to Shutters and identify your rooms as one family. They will mark it down and put any photos of all family members into one folder.
If you are extended family (ie: grandma or cousins) or friends, things are different. You can buy your room's package online for the discount, then buy one other room on board for 50% off (**someone confirm this is how its done).
Or, any photos of someone from your room with anyone else, (ie: grandma or friend from other room or even new best friend from kids' clubs) will be included in your package, but only because your room guest is in the photo. No photos of just people from that room will be included.
I think it gets more complicated if you have one room and DW has another, but grandma is staying in DW's room an the kids are with you. Not sure how that works.