In Karate what is a Double Fist Block?

Answer 1

I've seen a couple of moves that could be considered a double fist block.

There is the X-block where the arms are crossed at the wrists and tight fists are used. One interpretation is that it represents a block and a punch that are combined together.

The other would be where the two fists are next to each other, usually in a double high block. This could represent a double punch to break the hold on one's collars.