Hey iostream.h,
Welcome to T.F.!!
To me the concept of dual core technology, is that famous phrase "Two heads are better than one." By splitting the work load over "two heads", instead of having one, doing all the work. Enabling the processor to do more tasks, efficiently. Like I can encode or convert videos on one processor, and play a game on the other processor, at the same time. Where as a single core, would struggle.
I guess another idea, is so that we wouldn't have to raise the raw speed of the processor. Before dual cores, it was all about speed. The faster it's speed, the faster it is. But we couldn't possibly have such an insanely fast single core processor, because it requires more power, which leads to a heat increase. So we head towards multi-core processors, that are energy efficient as well.
Well, that's my two cents.