Those are known as hybrid cases, and there are quite a few of them floating around. I was at a walmart while on family vacation not too long ago, and I remember them having both the casemate pop and otterbox defender (which sounds more like what you're describing). We're going to need a better description in order for us to know which one he got, keeping in mind that the selection probably varies regionally for walmart. And what's the point of this thread? Do you want an opinion on the case?
http://www.case-mate.com/Verizon-iPhone-4-Cases/Case-Mate-Verizon-iPhone-4-Pop-Case.asp
http://www.otterbox.com/iPhone-4-Defender-Series-Case/APL2-I4XXX,default,pd.html
We could also rattle off other hybrid cases. The defenders are popular, but like all cases, they're not without faults. They're bulky, use silicone that stretches and tears and attracts lint, and they're not going to win any style points (if you care about looks). On the plus side, they'll protect your phone in most drop conditions and there's the screen shield.