There are different types of magnetic ballast system use according to the applications. There are single to two or parallel ballast system is installing in the home. Normally people prefer to use the two lamps ballast system. The advantage of using more than one ballast is that if your one lamp is not working properly than you another lamp will give light.
In the single ballast system if you remove one lamp than it want be affect more on the other lamp. It gives same glowing too. It is necessary to save proper lighting installed in you home. I thing your electrical consultant will gives you proper guidelines to gives better lightings.
The modern CFLs lighting system runs on the latest ballast technologies. It is one of the best systems that give better lightings in a more efficient way. It is important to select the single to two-way magnetic ballast system based on your applications.