Edge Print.
Actually, with the exception of the added photographers name what you are seeing is the original film's "edge print". This is frame number and film identification information that is exposed onto the edges of the film, outside the standard frame areas, during manufacture. Occasionally in the long ago past, some labs would print similar info just before the process the film.
The sample images may or may not be displaying edge print from the actual image. Its quite possible in post processing to "splice" one image onto a background scan of another film image including its edge print.
This is a modern echo of an old film style where a photographer would file out their negative carrier, or use an over sized glass carrier, in their enlarger to show some of the clear area around the image. They felt that precise framing in camera to the rigid aspect ratio of the the format was important (for whatever reason) and wanted to "brag" about their "skill" by including the raw edge as a border around the print.