There has always been a good deal of similarity between various examples of spice boxes. In the18th century, spice boxes were a specialty of Chester County, PN, where a handful of shops were responsible for many of the spice boxes still in collections today. It makes sense that there would be a good deal of similarity.
Chuck Bender, who is a native of Pennsylvania and, is an expert on spice boxes, sometimes offers spice box classes. Before his passing, Lonnie Bird offered a spice box class on a regular basis. And, Steve Latta's version maybe the best known among woodworkers due to the FWW article. But, if you look closely at all these masters' work, they are all remarkably similar, with the same basic case proportions and even the choices of ornamentation appearing comparable because the original Chester County examples serve as the benchmark. It makes perfect sense that different sources of spice box plans would have remarkably similar drawings.
I am starting my own rendition of a Chester County Spice Box. I purchased the Lata plans years ago and will probably use portions of his plans to dimension the case. But, I am planning to change the interior of the case to my own design which will have features seen both in Lonnie Bird and Chuck Bender examples. When I'm done it will not surprise me if there is another set of plans published somewhere that seem to be a copy of what I have drawn.