I have come across film cameras & lenses where the manufacturer's name was obliterated (filed or scratched off, etc). This was due to customs regulations that existed at one time. Photographers had to do this (or thought they had to do it) in order to bring their gear back to the US. I don't know the details of the regulations but you might run across gear where this has been done.
In a similar vein (please pardon the digression) it was once fairly common for owners of higher priced cameras to carve ID information into their camera bodies and lenses in the belief that it would deter theft or assist in recovering stolen gear. Of course, it ruined the value of the equipment at the same time but that didn't seem to occur to them. These engravings were usually very crudely done by hand with a sharp instrument. Sadly, I have come across many valuable items such as Leicas, Rolleis and other fine cameras and lenses where this has been done.