I am not familiar with your model so may not be right but on the models I am familiar with the dash acts as a backup for the ODO value in the Engine Management ECU so if the 2 do not match it will show the engine management light, the Dealer diags system has a routine to resync the ODO values between the 2 ECU's, I have not seen any mention of the capability in GS911 & as you would be aware ODO tampering is a sensitive issue with Govt's so a resync capability may be considered a problematic feature
On other BMW vehicles ECU's can also have VIN programmed into them to prevent ECU swaps between vehicles, there are some utilities out of China to "virginize" ECU's, not all work well I hear