Plate Numbers

I hope this isn't a dumb question. Why would there be 2 plate numbers on a single stamp?

I think it depends upon what you mean. This is a case in which a picture would be very helpful!

Stamps printed with multiple colors can have multiple plate numbers in the attached selvage surrounding the stamps.

Also, plate numbers may have "ghost" plate number impressions - I don't know why, but I have seen them.

You may be asking about some other multiple plate number phenomenon, so please elaborate!

Will put up a picture as soon as I can thank you orstampman.

Several Transportation Coils are known with two plate numbers. The most famous one is the 8.3 cent Ambulance ( Scott 2128 and 2128a ) where the engraver ( mistakenly ) placed the number 1 on row 1 of the sleeve 1 mm to the right and 1 mm lower than usual. The result is that a row 1 stamp may or may not have a plate number depending on how the web was cut. Row 2 can have either one or two plate numbers. Or one full one and a partial one. Plate 2 was printed together with plate 1, but it had the number placed correctly!

Peter

Here is the picture.

An explanation was previously provided at the link below:

https://goscf.com/t/20418

Actually, many plate blocks from the late 1960s created with the photogravure method had multiple plate numbers in the selvage. In fact, the stamp shown was actually printed by an outside firm, Photogravure & Color Co. of Moonachie, NJ.

What is curious is that there are actually six (6) plate numbers for this stamp (Scott 1335) but only five colors were used. I assume the 6th (two black numbers are shown) refers to the black used in the stamp design versus that used in the selvage.

Instead of two blacks, could one be a "paler" shade of black, or even dark, dark, dark blue? There is some very dark water in the image making up that stamp. Maybe there was a plate to apply this very dark water, and another to apply the black used for text.

Actually, I checked the 1967 Postal Bulletin for the stamp and it clearly references only five colors: red, green, blue, gold and black. However, black in the text of stamp versus the depicted picture is not out of the question, I suppose.

Another interesting point is that the print quantity was 120 million, which is much higher than most commemorative stamps issued today. Of course, back in 1967 there was no e-mail, and fax machines were only in their infancy, so the US Mail was the primary means of communication back then.

Thank you everyone and wt1 for providing the previous link.