Are you referring to a super-bright display and a normal display? That shouldn't be a problem, as long as you're willing to live with one screen brighter than the other. Just be aware, the EFIS (D100 in your case) determines the brightness control that goes over the DSAB network. Given that your D100 has the brighter screen, you might dim the D120 down too far if you ever adjust the brightness down on the D100.