Does it really have a 4 Go(2Go*2)in its graphic card?

I want to buy the Asus K551LN XO204H with the following configuration : -I7 4500U

-1TB DDR

-8 Go of Ram

-4G GPU (here is the issue.in the official website.I have found that there is only a 2 Go Nvidia Geforce gt 840M.I'm really confused because I went to a shop selling laptops and i saw the laptop and its specs .I typed the cmd Dxdiag everything was alright but when I Clicked at the display part I've just found an intel graphic card but I quickly realised that maybe I should go to Nvidia's settings However, I didn't recongnize the real value of my graphic card. I have found 4028 Mo in the dedicated video card . I'm not sure whether it has really 4 Go in the graphic card or not .One more thing I want to ask about .Can I upgrade my Ram .Thanks in advance .