Can you have two cellphones that have same number?

No. Unfortunately, not in the U.S.

Actually, it is possible, but may not be legal in all states.

Cell phones are programmed by the seller. Each cell phone has a unique electronic serial number (ESN) but that number can be changed. This is called cloning. A cell phone can be cloned by those who know how (illegal), but you may be able to get this service for an additional charge from the service provider.

Your best course is to ask.