I also have 1.0 CE and bought the 2.0 CE as well. Gave it to a friend and they can play fine. They just need to download the client from the URL already posted and register the code to their account.

Strange part is that you cannot upgrade from Normal to CE with an Full CE code. You have to either use the CE code from a different platform (use PS3 for PC, or PC for PS3) or you need to use the CE Upgrade purchase in the mog station.

Alternative is to add the CE as a new service as oppose to the existing normal edition service.