Welcome to the forum! This is a common question 
That’s because your brushstroke in Procreate has a thickness that a laser will read as two lines. If you wanted to engrave it, it would look exactly like your original design.
I don’t know Procreate, but either you need to make your brushstroke a single line rather than a thick line, or in Illustrator you need to break apart the two lines and delete the center ones so it just cuts out the outside ones. Keep in mind that if you cut that out things like the centers of your B will also fall out since nothing is holding it in.