I'm not as old and as senile dementia afflicted as Joe "I want to sniff, lick, and paw your 10 year old daughter and stick my fingers in your wife's coochie while I ramble on about Corn Pop" Biden, but between age related short and long term memory loss and all the hard drugs I did back in the 70's and 80's, along with the hundreds and hundreds (some people would say "thousands", and they might not be wrong) of firearms I've owned over the years, a lot of recollections get kind of hazy.
But I definitely remember having "something" that was original German WW2 electropenciled. Probably on a Mauser rifle......I'm thinking (but not 100% sure) it was a German reworked Czech VZ24......could have been a bring-back Kar98a though, I've owned a few of those too. I might remember what it was later, I might not. Anyhow, I'm thinking it was a bolt part, a firing pin, it seems. I don't think it was a safety or cocking piece, but can't swear it wasn't.
Anyhow, whatever it was, it was definitely a straight, honest, never dicked-with WW2 vet bring-back. I remember being surprised to see the electropenciling on a WW2 "war trophy" firearm, as most of the electropencil stuff you see (other than National Match '03 Springfield bolts) is post-war, usually Central or East European Commie stuff, like the Russians, Czechs, Bulgarians, etc. did.
But the short answer to your question is, "Yes, it has been known to happen".