If I think about the old machines, which may have detected iron slugs, not these, and the time when this one came from, the Great Depression in US and Canada, maybe I'm not as surprised?
Old vending machines weren't as sophisticated so a dime might have been worth the time to file down a cent. Maybe I should be surprised there aren't more of these?
My other slug is a quarter. I've seen some odd things come through the registers. I worked at a book store in college, managed a bowling alley and filled in at a Chinese Restaurant on Sunday's for years.
Last auction I bought a bunch of "foreign" coins. From the mix, including Canadian around the world, not a traveler. There were also tokens, medals and mystery items. I think maybe the owner had something to do with vending.