C16 Block With "Ghost" Plate Numbers?

What do you make of this block of 4 C16 stamps? I'm curious how the "ghost" plate numbers got to be there. It can't be set-off from a stacked sheet for multiple reasons, particularly because the plate numbers are not mirror imaged. It is as if the plate numbers were partially erased from the plate itself. The block shows 2 numbers - 20607 and 20606. The fluorescent pink/red streaks in the scan are just on the scanner - not the stamps.

What explanation can you come up for this?

Matt

The two plate numbers shown are the correct ones used to print C16, but I've not seen anything like this before.

Almost looks like ink starvation on the edge of the plate, but like the uboatnut I have never seen this either.


Peter

It is up for auction right now:

http://www.ebay.com/itm/201904389519/

They are from a still wet plate number transferring to a roller and then back onto the stamp paper, but in a new place. I have recently sold one like it on a 937 on ebay (you can find it by searching 937 and they selecting sold at the left and scroll down to April 6). It sold for a whopping 99c.

Thanks Eyeonwall! That now makes sense how that could occur.

Matt