Copy-pasting icons from the same page sometimes adds the icon to the Attachments of the page

This bug is quite inconsistent. The following steps to reproduce are the ones that I had most success with:

• go to an already existing page/create a new page (with some text) and save it
• insert an icon the standard way; to open the insert icon module either
  • use the /img macro or
  • use the icon button in the editor's toolbar
• go to the icon tab in the module, write "tick" (this should be the same with any icon name) and click on Select
• add an alternative text and then click on Insert
• the first icon is inserted and not added to the attachments
• select the newly added icon
• copy it (CTRL+C)
• go to anywhere else in the same page's content
• paste the icon (CTRL+V)

Expected result: the copy-pasted icons are inserted to the page just like the first one

Actual result: sometimes, the copy-pasted icons are re-uploaded to the page with new names (this could possibly be caused by how the clipboard interacts with attachments), but sometimes they are inserted correctly as icons (not attached)

Some extra details:

• this happens on 16.x and 17.x, I never reproduced on 15.x
• the new names for the attachments are sometimes new random IDs (which might point to the fact that the editor/clipboard considers the icon as an image), but very rarely it has the "icon_name.png" name (in this case "tick.png")
• the copy-pasted icon must be from the same page. If you copy-paste it from another page, this will always happen (this could be explained again by how the clipboard works)
• in the source of the page:
  • whenever I do not reproduce, the copy-pasted icons have the exact same structure as the initial icon: [[image:icon:tick]]
  • whenever I do reproduce, it is something like this: [[image:image_name||alt="tick"]]
• adding the icons by inserting them everytime instead of copy-pasting them will always work correctly (but it is more tedious)

I will add more details whenever I will find them, as I am still trying to find a consistent way to reproduce this.