sounds as tho they aint as reputable as them would have you believe.
as Mrbilluk stated, any pukka group n ecu is virgin when it arrives to you and is paired to your car with the immobiliser data once its connected and powered up.
The only issue is of he has a tuned ecu file from sum1 elses vehicle which he is trying to apply to others and cannot due to this immobiliser data which is a bit lame.
Any proper tuner (pmurray on here plus a few others) extracts your data and works on that, not applies a diff dump to your car.