I think it matters somewhat if your decks are going to be monosphere versus mixed sphere. I think playing with one monosphere (one color) deck would probably be a mistake. If your decks are only one sphere each, then I think you'd want to play with two of them. If your deck is of mixed colors / multiple spheres, then you can certainly play with just one.
Hi Juan, you can do both but in my opinion playing two-handed is in general a much more rewarding experience. The interaction between the decks is a crucial part of the game and your future deck building possibilities are much bigger. Either way you'll have fun! and welcome to the comunity. Søren