Message from UniFlash about Boot block

Recommended by Wim's BIOS...

Hi. I tried to use UniFlash to hot flash a chip from a different motherboard and I got the message:
Boot block mismatch. Proceed anyway?
So I tried to flash it including the boot block, and I got the same message.
question: Is this "boot block" the one of the system running currently (of which I have removed the BIOS CHIP) or is this "boot block" the one that is already in the chip of the another motherboard (the one just about to be rewritten)?

[Rainbow]

Flash including the bootblock and answer Y.
UniFlash compares the bootblock of the image that's read from the chip (at startup or when using the redetect option) with the image you want to flash. If the bootblocks don't match, it will ask this question.