I do pretty much the same workout, but on different days.
I definitely have no problems squatting and DL-ing on the same day. One thing I do is, and this was a training tip a while back, is prioritize. One of my lower body days I'll squat first, the other I'll DL first. Seems to help one of the two from becoming a weak part of my routine, as I would probably always squat first, it's my favorite.
I have always believed that working your back/lower back is better on your lower body days than your upper body days. I'm no expert though, I just know what works for me.