C12 Double Transfer?

From my junk box, I have this duplicate. My other stamp is nice and clean around the 5's and the letters at top. This one definitely has some "ghosting" to the left of each "5", in the middle of the "C" in cents, and to the left of the "U" in United. Is this a double-transfer, or just some type of skip?

Looks like a dry print to me.

I was wondering about "dry" versus "wet", but see that the first dry printings on US Air Mails did not occur until 1947 with C34, so this is a few years too early (1930). Probably just an underinking, but since there is a note about double transfer (plate 20189), I was intrigued.

The entire stamp has similar flaws. If you look at the beginning of the "U" in "UNITED" and the around the "C" and "S" in "CENTS", there are similar issues, that suggest that under-inking is the most likely cause.

Wet and dry in printings refer to the moisture content of the paper. This stamp was a "wet" printing. Underinking was frequently caused by the paper not being quite moist enough to hold the ink in all the lines of the engraving when it was printed. That is what I meant by a dry print. This is as opposed to the roller simply not getting enough ink in selective locations.
Dry prints frequently happen on first issue revenues; printings also occurred when the paper was too moist as well. Those would wind up blurred.

Agree does not look like a DT. Thanks for posting!