Audi Q7 4.2 TDI S Line ECUs

Hi, Ive just purchased a used 2008 Audi Q7 4.2 TDI, its a none runner due to water ingress into the fuse box. The seller has had both ECUs repaired, but they are currently both off the car and I'm unsure which one is number 1 and number two ? I'm also unsure which ECU goes where, ie left/right of the car. I've done some research and which says number one ECU is the Master and number two ECU is the Slave, my research says all files are identical except for eeproms 95320 ? which means absolutely nothing to me ??? Does it matter which side of the car the ECU are installed ? Would really appreciate any advice, thank you, regards Graham.