infact, I coded one of the fobs to two different TF's I've got.
I don't think that this will work longer term. The Pektron and fobs using "rolling code" technology.
This is the reason that only new, unused fobs can be coded in.
The 22 digit code relates to the unused state of the fob; once it has been used a few (no one seems to know exactly how many) times the code in the fob is no longer the one on the bar code because it as "rolled".
My understanding is that there is a "window" meaning that the code in the ECU must be near enough to the one in the fob or it won't be recognised.
If you use the fob on car A too many times then the code in the fob and in car A will roll out of the window that car B will recognise and it will no longer work on car B.
If you keep this fob as an emergency backup and never use it you might get away with it but use it too many times on one car and it will stop working on the other.
That's my understanding anyway.
Additionally I have (for the time being) created a 22 digit barcode checker here
http://pscan.uk/features/pektron.html
This uses the same algorithm as that is implemented in pscan.
If anyone gets a 22 digit code that
doesn't work on the checker then please post the code here and I will try it on my T4 and make see if that accepts it.