Just for future reference, you don't even need to go to Google to answer this type of question. @:-)

On this very FT page, there is a bar that has "My FlyerTalk -- FAQ -- Calendars -- New Posts -- Search -- Quick Links -- Log Out" on it.

Click on "Quick Links," then "Airport Code Lookup." When you look up PVG and SHA, you'll see they have different names: Pudong and Hongqiao, respectively, as already explained by others on this thread.

(Furthermore, I've never heard of one airport having two different codes. Have you? )