I bought new dell 745 system(desktop). I paid for Core 2 Duo 2.1 ghz, but system is showing Core 2 in properties. It should display Core 2 Duo instead of Core 2. Is Core 2 and Core 2 Duois same thing?
Core2 is the name is the name for a microarchitecture. It encompasses a whole CPU family
There are single core CPU's based on the core2 architecture.
Thus calling a
Analogy: (cars with engines)
In all cases it is safe to call the car 'diesel engine'/'core2' based.
All this means there is nothing obviously wrong.
However you can easily check things:
First see which CPU you are supposed to have.
Once you have the model of your CPU you can find more information about it on this site.