Mystery 1881

[Road King]

Hi everyone, i recently was checking the butt plate on a model 1881 to see if numbers matched. When I removed the plate, I discovered 2 machine nuts embedded in the stock. They were not glued in just loosely setting in the wood. The rifle is in very good condition. My question is, has anyone else encountered anything like this or have an idea why they might be there. Rifle is in 6000 serial number range.