How to extract code on one DT-06 board to another board? I have two DT-06 boards DT06 datasheet.

The board stock firmware provides Web UI for wifi/network/serial setup. I've replaced the firmware on one board with other sketch; but now I want to revert it to the stock firmware. I cannot find the stock firmware source code anywhere. The DT-06 manufacturer also won't give it out.
Is it possible to extract the stock firmware from another DT-06 board and put it back into the other DT-06 board?
Thank you.
Okay. I found a way to extract the binary file (stock firmware) from one DT-06 and flash it to another modified DT-06, by using esptool command
/*To extract firmware */:
esptool.py -p COM4 -b 460800 read_flash 0 0x400000 dt06_backup.bin
/*To flash the backup binary file to another DT-06 */
esptool.py -p com4 write_flash -fm dout 0x00000 dt06_backup.bin