For the first 13 years of yorkie ownership, we had 1. Then we decided to take the plunge and get 2. 2 are more than twice as fun as one, as you get to see so many more behaviors than you do with one. It's so much fun to watch them play chase games and compete in fetch. It's also amusing to see how one wins the battles sometimes and then the other.
The only down side I really see is its more expense, and harder to find another owner to watch your pack when you go on a vacation and cannot take the Yorksters (we dont use kennels).
