I recently bought some 4” square junction box cover plates, made by Raco. As I was installing them I noticed one side was stamped (into the metal) “underside”. Never seen this before. Is this something new? Am I missing something here, or is this just possibly part of the manufacturing process? To me, it looks like a standard plate with the exception of the stamping.

The only way, I could think it makes a difference is if there were knockouts present or the plate could be used for another purpose and that is an artifact of a blank plate.

KISS,
Nope, it's a solid plate, & the mounting holes line up with the corner of the boxes. Went back to the store and all the plates are stamped. THe bar code on the plate matches the one on the box, labeled 4" square plate... hmmmmmm

Then maybe this piece is used to manuafactur another product. e.g. transformer attached to a plate. The other product may have holes in a certain direction or the orientation is used in the manufacturing process.