When WordPress downloads a plugin zip file it downloads it to the WP ‘uploads’ folder which is divided up into sub-folders representing years and months. After it has unzipped the files while copying it to the correct location it then deletes the original zip file.

Except that sometimes it can’t perform the delete. And if you then subsequently download a second version, rather than overwrite it – it adds a -1 to the end. And this causes havoc.

So far we have been unable to determine why this sometimes happens as well, of course, as being unable to change the WP core code.

When I say download, I am talking about downloading a plugin form:

https://simple-press.com/download-plugins/

and downloading to laptop/macbook. It is the macbook that alters the filename because a file with that name already exists in the directory (because I must have already downloaded that plugin in the past OR coincidentally a file of the default name already exists in the download folder). And then attempting to upload that simplepress plugin with the altered name causes the problem to occur.

not much we can do if your computer is renaming our file…  just takes a bit of care… and as you mention, its easy to resolve if incorrect named plugin is uploaded…