If you add another table it wont take you long to get the hang of observing both tables and getting a feel for all the players.

I play 4 tables and I usually have a good idea of whats going on because (at most sites) I can fit all 4 tables on the screen with hardly any overlap so I can watch them all. Obviously you cant pay as much attention to each table as if you were only playing 1 table but if you practise you will eventually find you are remembering things even with 4 tables. HUDs help alot. Taking good notes helps even more.