do you plan on battling or is this just an investment?
edit: well to cut the chit chat, if you plan on battling, combining cards is essential for your ability to be able to perform in battle well, something that will get you active money, or you can keep em separate to help them retain their value, something that will theoretically get you money passively. its all on what kind of card holder you are and how exactly you want to approach the investment.