Have a look at the blue "background" and you will see that the apparent color difference in the badges is likely due to different color balance (lighting conditions) in the photos. That's presuming that the blue wrap is the same on all four drums. Yes, the lettering could be school IDs. If the drums had blank badges a school (or even a private owner) might have preferred a serial number for insurance or inventory purposes. Who knows.
I not so sure about that sheen and lighting thing.
Anyway, the serial number badges had this scratched surface on them. The non serial and Resto badges don`t.
