Thats a really bad way to phrase it tho, king. 2x 2ghz cpus do not equate 4 ghz.
I have a dual MP2200, it doesn't run at 4400+, they both run at 2200+, and for regular use, only 1 cpu is used, only when I do my rendering, video editing or massive photoshop work do the second cpu come alive.
A better analogy would be a 2ghz system with double the lung capacity