If I write same value to same location again and again,
will there be records created in D-flash each time, or the Emulated EEPROM hardware will understand that its a same value so do no create record again.
To optimize the EEE write cycling, the S12XE implementation automatically filters out creating new
NVM records for aligned word data if the data value written to the EEE RAM is the same as that already
in the RAM. Writes of byte or misaligned word data will always create new records.
I'm unable to find confirmation for these words in datasheet, but you could check the time how long MGBUSY flag is set when you write the same data, and how long it is set when writing different data.
