Both sizes of dishes have a newer style LNB that receives the third Shaw satellite. The large dish is only used in fringe areas of service, like the extreme north. Almost all aplications in central Canada the small dish is used.
To get the second location working you will simply need to purchase the second LNB. Instalation is just switching them out. You'll need to know the size of the dish you have at the cottage to get the right LNB