Then it's entirely possible to inherit a recessive for pigment in back of the iris (gray) and a recessive for pigment in front of the iris (green) and end up with a child with brown eyes.
Eye color questions.
My Scottish ancestry husband had clear bright blue eyes and red hair (according to a recent FR post that may mean he has some Neanderthal ancestry. I have hazel (northern European) eyes. When our two sons were born they had dark brown eyes. Since my husbands eyes were completely recessive, the brown had to come from me. Probably my Prussian German ancestors had some ancestry from the Mongolain Tartar invasion of Eastern Europe. Since oriental traits are often recessive to caucasian ones, I must have a dark brown semi-recessive eye color gene which overmastered my husbands true blue gene.