Not sure if this was really mentioned/explained, but the reasoning for copies of some maps between the two banks is for speed optimization. Because the 8051 Micro controller being used only has a 16-bit address bus, and the AN28F010 flash chip needs a 17-bit address bus, when the cpu is executing code and needs to switch banks a routine to change that 17th address line is run. If I remember correctly the 17th bit line is multiplexed with some other function. The M4.4 system has double the memory as M4.3, but does not need all that space. That's why there are copies of maps commonly referenced by the software, so that way the CPU doesn't need to switch banks which could potentially mess with operation of the engine. So essentially, if you edit a map, make sure you are editing both, otherwise the car will run off the original tune's values when executing code from the other bank.