They are totally different engines. Is your gtd brand new? Are you mistaking a regen for the fans cooling after you've turned the engine off?
Yes the fans will run on for 6/8 mins after switch off to cool the engine after a regen has been interrupted.
From my experience the 'fan run ons' become less frequent with more miles on the clock.
The gtd doesn't do passive regens and the fans after switch off are cooling the dpf down not a continuing dpf regen. I think its been well documented that the mk7 does not do passive regens. The addition of adblue should effectively mean a dpf will never be clogged again.