I've already got full Melodyne Editor and Addictive Drums 2 with several adpaks as well as all the stuff that came with X3 producer.  Do I need to reinstall things like melodyne essential or the Trial AD2 producer thingy??  I'm thinking no.
 
Plus if you already own AD2 do you get any freebie adpaks with the Platinum upgrade??
 
 

1.  No you do not have to reinstall the vsts and extras you already have installed.  However, the Command Center will not know you did not install these; that is not a problem, but the red light stays on for those programs not installed by the command center.
 
2.  You get three other ADpaks, 3 midid paks, 3 instruments of your choice if you already own AD2.  I grabbed three great Adpaks.  This alone covered my expense for the Platinum update.  No brainer.  Cakewalk will give you a serial number for AD2.  Just register it with XLNAUDIO and you can pick any three adpaks, etc that you want.

Yes, there are adpaks - when you do install for ad2, it'll attempt to reinstall the XLN installer - just cancel it, and then a doc will pop-up with adpak codes when finished. You can choose/install the adpaks directly from within the XLN installer.

Your other option is to just go to XLN site, log in, click on "register product" 
and insert the code you received from Cake.  Then you will prompted to
pick you Adpaks, MIDIpaks, and Kit Pieces...

Both ways work...

Supa Dupa!!