Drawing A Mental Blank: Term For Washington-Franklin Bicolor Fantasies?

I could have sworn that there was a technical term for these, but perhaps I'm misremembering.

Early 20th century U.S. covers where the sender cut up Washington-Franklins to create bicolor stamps, typically using the frame of one stamp with the vignette of another contrasting color.

These were technically illegal, but were typically condoned.

"Fantasy" is accurate, but I thought there was a more specific term.

I don't recall ever hearing a specific term for them, although they were a popular thing to do in the 20's and 30's, and not just with the W/F issues.

collage?

Inlaid?

Prank?

Let's create a new one. How about

Stampus imatatio etymology

(My ridiculous Latin version of stamps, imitation multicolored)

I believe Bill Weiss used the term "transposed vignette"

Maybe "bicolor". Here is an article from Linn's.