There is no shortcut or action to duplicate a bookmark in the bookmarks editor.

Here is an example of a situation where it is very annoying: I have a "translate in English" bookmarklet (a snippet of Javascript which calls G**gle Translate), and I'd like to have the same for French. It's just a matter of duplicating the bookmark, and changing "en" to "fr" in the URL. Unfortunately, it is not possible to duplicate the bookmark, and there is not even an a menu item to create a new bookmark from scratch.

Incidentally I tried pasting the Javascript "URL" in the location bar and to do "Add Bookmark", but instead of using the Javascript snippet, the new bookmark uses the real URL of the currently displayed page. Which means that I couldn't even achieve the simple operation I wanted to do. (perhaps I am dumb and overlooked an obvious way to do it...)