Duplicating bookmarks in Google Chrome
From experimentation, it seems this behavior is only exhibited when using the Ctrl+D dialog to add a bookmark. Hence, Chrome allows for copies of the same bookmark, but a "feature" of the shortcut interface is to move the bookmark if it exists elsewhere. Given this, there are multiple solutions to create copies of bookmarks in separate folders.
- You can open the bookmark manager with Ctrl+Shift+O, then copy and paste bookmarks from inside the manager.
- You can show the bookmarks bar with Ctrl+Shift+B, then drag websites from their address bar icons into multiple folders. You can also use copy and paste here as well.
Admittedly, these are somewhat tedious solutions, but as far as I can tell, there are no other ways.