Firsly it does not mean the processor will run at double speed. It's just that there are two logical cores inside the single processor.
The Intel dual-core (Dual cores and Core 2 Duos) processor consists of two complete execution cores in one physical processor. Imagine that a dual-core processor is like a four-lane highway—it can handle up to twice as many cars as a two-lane road without making each car drive twice as fast.
Similarly, with an Intel dual-core processor, you can do more at once than ever before, without slowing down.
This little video mught help you to get a quick ideo of multi core processing in intel processors: http://www.intel.com/technology/product/demos/multi/demo.htm?iid=tech_dc+demo_how-mtc-works
If you want more information you can also read more on this link: http://www.intel.com/products/processor/core2duo/index.htm?iid=tech_multi-core+body_core2duo
Core 2 Duo processors are more powerful, energy efficient and provide better performance than single core processors.
Hope these links will be helpful to you.
More information about Intel® processors can be found by searching the processor product database (http://ark.intel.com/). If you are unable to locate (search or browse) either the Intel® processor that you are looking for, please send your feedback. (ARK_Support@intel.com)
Thanks for your detailed answer i finally understood how those "Monsters" work.