I did some searching here looking for an answer and came up with two posts.
GCC found the same on his '70 vert...
<<<The inserts on these hoods have a diecast piece approx. 12" long and 1" wide with 2 attaching studs that attaches to the main body of the hood insert. I have two sets of these that appear to be factory, but they mount differently. They both have the 2 studs, but one set has small screws mounted from the front side, and little round nuts on the back side. Is this possibly a difference between '70 & '71 hoods, or did some hack add these?? Thanks, J->>>
Steve mentioned this in May '05
<<<Speaking of factory mistakes, did you catch the article in this month's MCG on the untouched '70 'cuda? One of the hood inserts was put together with screws through the front of the inserts and the other side was done with studs on the backside. Could it happen? Yes....did it? Sounds like a good mystery to solve.>>>
Because one was in primer I assumed it might have been replaced, but upon closer inspection there is burnt orange paint under the primer, so it is original to the car. One of the posts stated it was a diference between '70 and '71 model years. Mine was built late in the '70 model year. Sounds like the factory had scoops with and without the lead inserts for the front screws and they installed mixed pairs.