There are commonly used versions of Chumash Haamek Davar in which the respective Haamek Davar commentaries differ widely from one another. I mean that the differences are not a word here and a letter there but entire swaths of text — often a list of examples or a tangent — that are present or absent.
How did it happen that such widely differing versions are in the market? Did the author himself publish differing versions at different times? Or did he not publish at all, and these were taken from different manuscripts — and by whom and when and why? Or what?