Booting Windows VHD with custom boot flags

[glockmane]

Tried both PowerISO and UltraISO both cannot replace both bcd files.. I could replace the "bcd" then rename it to "bcd_" then added the "BCD" and it replaced it correctly but then I cannot rename the "bcd_" back to "bcd" cause he cannot handle two files with the same name..

What's the difference between the two bcd files and are they both needed?