Let me guess. . . is that 2nd shield a CalSci? I bought one from them last fall and noticed the same thing. You're not missing anything. They just drill the holes a little on the big side and that allows those center screws to go through if it's positioned just right. I contacted the manufacture and they assured me that it wouldn't cause any problems. So far it hasn't. Here's a thread that I started last year with the same question:
http://www.zggtr.org/index.php?topic=4291.0