keys made in the vw secure key room come partially pre-coded to your vin. this then gets paired to your car using the official dealer diag tool (odis) and gets registered on the geko server (immobiliser/security server). This means somewhere in Germany a computer always knows how many keys you have for your car. A non-genuine key will not be pre-coded so cannot be added to the server or programmed the official way. Auto locksmiths that aren't using odis will be simply cloning your existing key, which doesn't have a great success rate on newer cars. I've seen them try to add a new immo ID to the car for a new key and it can cause all sorts of weird issues. I fully appreciate how extortionate the new key prices are from VW but it really is the best way to avoid problems. I won't even attempt to program a key for a customer unless it's one I've supplied through official channels or if they have a receipt from TPS/VW.