1930s oddball card printing plates
 

I met a collector today who showed me these images of what appear to be printing plates. The images are the same as in the Butterfinger set, but they are way smaller, like the size of strip cards. Can anybody identify the set? Thanks, Chris

it seems like if they were printing plates the images (and writing) should be reversed?

Not with offset printing. Not saying that's where these are from, but this subject comes up frequently when people ask about printing plates.

Offset Printing:
https://en.wikipedia.org/wiki/Offset_printing