I'm sorry for the misunderstanding but i now how to duplicate a spread or move it. 🙂
I was just trying to highlight a possible UI problem, because: why if i need to duplicate a spread or a single page in another file, i can do it by the "move pages" option and not by the "duplicate" one? Wouldn't it be more natural clicking "duplicate" and then selecting "on the current document" or "other"? I’m just asking for an opinion, that's all 🙂 .