FDC Cachet On A Non-Fdc Cover

The Virgin Islands FDC of 12/15/1937 was issued solely from Charlotte Amalie, VI:



While DC is often an issuing site the following day, it is not in this case. Yet the below VI cover, lacking the First Day of Issue cancellation, has the VI FDC cachet with a DC PM:

papa, is there a question here?
The second cover is obviously not an FDC



Peter

Sorry. The question would be, how/why would DC have a VI FDC cachet when they are not an issuing city, or is this "error" a common occurrence?

Papa, I think you are overthinking this. Washington DC has no cachets, the sender did. He used an FDC cachet the day after. There is no error here.
The cachet is not usually issued by the US Post Office, but by a cachet maker. They sell them to regular collectors like you and I. We can use these for whatever we feel like


Peter

"DC" had nothing to do with the production of that cachet. It was just one of many produced by private individuals or companies. This one is a Ralph Dyer cachet (see "Rdyer" at lower right), designated M-42 in the Mellone catalog nomenclature, indicating at least 41 other cachets recognized in the Mellone catalog. While postal authorities in the early decades of the 20th century often produced unique cachets for special events, often rubber stamps, from the 20's onward the more artistic types of cacheted covers, like this one, were privately produced. Sometimes the covers would be sold to subscribers who would get the FDOI postmark on their own, but often private firms produced them also. Dyer became an early producer of hand painted cachets, besides the printed cachet seen on this cover.

"2nd day" postmarks from Washington DC from this period are relatively common, with cachet or without. When listed in Scott, they are usually priced at a fraction of the price (like $1.25 versus $10. from the issuing city).
The only oddity here may be, why does Scott list the Washington DC second day cancels for most everything from #772-#795 and then stops right before this one, when the 2nd Day practice still continued and those covers certainly exist in great quantities.

The acronym FDC means that the envelope itself is an FDC, only it is not official.
I have received unofficial FDC circulated, even two months after the issue date.
Just today I received this with cancellation from FDC from behind.