50cCL2B-SO 'Yellow on top' just discovered by Rein

Rein has discovered this remarkable variety. Here are two used blocks of four.



Notice the vertical lines from the background plate printed on top of the foreground plate.





Here is the second block.







Without this level of magnification (2400 dpi), it is impossible to see this variety. Here is a normal example from the worn state of the plate (NGR).