No worries, that is the layer of fat that separates the two muscles, so essentially those center slices have meat from the flat, and meat from the point. I actually prefer that 5" to 6" of slices. The lower left in my photo shows the same fat seam.
In this photo, flat on the right, point on the left, you can see the natural seam between the two muscles, and where that fat layer lives. You usually only need the spine of your knife to separate the muscles.
EDIT: I don't know why that area is darker, is usually is not and 4 briskets in a row would make me assume it's not the cryovac juices (purge) which is a mix of myoglobin and protiens.... not blood. Are you wet aging? What is your injection?