Thank you for your answer, theducks ! What I understood from it, because I'm a total noob in epub structure, led me to a possible solution.
So I...
- Opened the epub in Sigil.
- Removed the 'cover' status (semantic ?) of both the first html file and the image included in the epub.
- Renamed the image cover2 and changed the appropriate file name in the first html file. Was it necessary ?
- Used the 'add a cover' option.
I was having serious brain farts with the way calibre handles things and also had trouble with the fake blank cover reappearing upon an epub to epub conversion. While similar, Sigil creates an html file when adding a cover, which avoided dealing with temp file.
Would it be considered a good way of solving the matter ? Maybe more importantly, I hope I make a minimum of sense
