can someone explain what this is  

it's a hardware dump... for OCD collectors only.

Every flashcard has its own internal ROM chip similar to a regular game cartridge, but instead of game code it has the code to boot the DS and load in the flashcard menu. Technically speaking this is the actual "firmware" of the flashcard, and the files you download and stick on your microsd is the "kernal". But to the average user it is worthless, just a collector thing. Maybe flashcard manufactures can use these to make clones.

Yay! Clones, because R4 clones aren't annoying enough,

Lawl this statement, R4 isn't even original. R4 is an internal rip off of the M3.

cmiiw, but M3 is R4 clone?
or the other way around

M3 goes back to the GBA. maybe further back.

does someone have to ask this every time they release one of these?

can someone explain what this is