At least not for GSM-type phones. The phone number sits in the SIM-card and your provider won't give you 2 SIM-cards with the same number. If you don't believe me, just call their customer service and order such a set of 2 SIM-cards.
I suppose it won't be different with CDMA-phones (like Verizon has).
With my POTS-phone I don't have any issue with having 2 phones in the house (we even have 3 that are connected in parallel, so ring together until I take one). Could even be more than 3 using wireless (DECT) phones.
But cell phones are limited in this respect. Different technology.
Kees
Is it possible to have two cell phones (one at each end of my house) that use the same phone number?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic