Hi, thank you for your answer :)
I perfectly understand what you mean: there can't be two different images linked to the same URL, this is simply no possible.
Also my bad: I incorrectly confused the new image with the old image, now they are correct.
The issue is that the icon in the gallery panel seems to be linked permanently to the old image (the link is correct, it lead to the new one).
I tried to delete the image and to upload a new one, but as soon as i put the name back the icon becomes the wrong one :(
Regarding the issue of images with the same name, as a painting/photography enthusiast I have to say that there could be a case where I wanted to give the same name to two different images, for example two self-portraits that I will call "self-portrait" or two landscapes that I will simply call "landscape". I would like to avoid calling them "self-portrait-1, self-portrait-2..." and so on. In the images I attach you can see how the case is handled by my old application, which unfortunately I have to abandon: the names of the images in the caption are the same, but the application takes care of changing the URL of the two resources by itself. It could be a nice improvement for this gallery too, maybe I can bring it up as a feature request :)
That said, thanks again for your time and kindness.