Ecu question about swaps

[thejuzo]

My car is 1996 automatic, I have metal case ecu 7201f. Im going to buy spare ecu incase something goes wrong flashing the current one.
I found ecu that is from same year car and it is automatic too, with ecu 7201f too. But is it 100% compatible or will it trigger immobilizer?

 

[BCX]

VR-4 didnt have factory immobiliser.

 

[thejuzo]

VR-4 didnt have factory immobiliser.

I found part seller, who is willing to sell ecu from his automatic legnum year 2000. Ecu has part number on its plastic cover "MD340289".

Is that ecu compatible with my car

My car has old 7201 metal case ecu
Automatic with tcl.