Holes in fender?

[71CHEVYSHORTBED402]

When I pulled the RH inner fender some time ago, I found that someone, perhaps GM, didn't line-up the inner fender correctly. They drilled into front fender pocket and used a sheet metal screw instead of using the fixed nut as intended. It was off maybe 1/2". Someone suggested the inner fender was an after-market, but I wasn't convinced.

So today my son and I did a trial fit to determine why, and it became clear it was just laziness. The fenders line up fine, they just did it wrong. However, we noticed these holes on both fenders pictured below. They're located in approx. the same area on both fenders, only the RH fender has one more hole. I don't see a purpose for these holes, production? Have you seen this before?