[kiwidude]

Cool, let me know. The conditions on which it will keep an existing cover xml page are based around (a) whether it has any *other* images on that page, and (b) whether there is any text content on that page. If either of those conditions are true, then rather than removing the whole page it just removes the link to the cover image and leaves the rest of the page as is.

So if you have an ePub that doesn't have a "real" cover page, but incorrectly (Sigil can cause this issue) has marked the first page semantically as a cover, you don't lose any text content from the book. I have seen this happen with calibre conversions in the past, I believe it has been fixed now with the same sort of logic.

Edit: I should add, this is all assuming the plugin is able to "identify" the existing cover page. If there are no guide entries indicating a cover, or no meta tag entries pointing to an image, then it won't know what page the existing cover is. So it will just add a new page at the front, just like a calibre conversion does. These are the really badly published epubs, that hopefully are in the minority.