HR normally gets the feedback within 1-2 days Max. after that that they take ther own sweat time to make an offer if you have been selected.This normally is due to the fact that HR is slow and also their approval process takes time.
Their offer is based on the feedback from your second interview.So they know if you are getting in or not.
Call your HR contact and ask them straight away. You are entitled to know the result after 2 weeks.
I pestered them with my phone calls .if they say they'll come back to you soon ,ask them which date .if they dont, call them back again. They cant withdraw your offer if you do this ,they dont have the power to do so .
Hope this helps..