Yes this is correct. Optiarc seems to have released drives with an updated bootcode. While I haven’t seen this bootcode yet, the official firmware updates consist of two firmwares - one for each bootcode.
The flashing software (original or Binflash) then have to query the drive for the actual bootcode and flash the corresponding firmware. So while the files are now twice the size of previous firmwares, the data sent to the drive for flashing is still the same.