if i had 1 processors with 2 cores and speed is 1.0 ghz, those core be sum and the result are : 2.0 ghz?. i need official document explain that
No, the result isn't 2.0 GHz; it is still 1.0 GHz.
You can start with this page to find documentation on the processors, by type and generation: https://www.intel.com/content/www/us/en/products/docs/processors/core/core-technical-resources.html.
I suggest that you also learn about symmetric multiprocessing: https://en.wikipedia.org/wiki/Symmetric_multiprocessing.