Most maps are deliberately inaccurate in subtle ways. You can't copyright facts, so cartographers use fictional places and deliberate errors to protect their work. If these features appear on another map, then it's reasonable to assume that they were plagiarised. Historically, cartographers have often created settlements or roads where none actually exist; inventing fictional names for districts or mis-spelling some…
https://en.wikipedia.org/wiki/Copyright_in_compilation
This is precisely why mapmakers introduce deliberate errors, so they can prove that a plagiarizer produced a copycat atlas not by recompiling from the basic facts, but rather used the compilation as a starting point.