I just got this one in the mail today, a very scarce R18c double transfer commonly referred to as ‘eggs north’, where the outlines of the numeral ovals are transposed to the north.

There is also an ‘eggs west’ (which I am still looking for) although that DT is not as bold as this one.

The second image is much higher resolution with the DT elements highlighted. It looks like there might also be something going on through the tops of the letters of “proprietary” in the bottom scroll, especially the OP and the ET.