986 Boxster - Spare key/fob

[Skullbiker]

Having changed my ECU/DME (rear boot), Immobiliser/Alarm box (under seat) and key fob I need to get a second key made so that I have a spare.
Can anyone tell me : I have the keyfob from my old immobiliser and ECU combination - can the specialist/dealer programme/match this to the new set up as my spare ? or do I need to buy a brand new fob( and have that programmed/matched)

Thanks