I don’t know if it is an intended behaviour or a bug: In the “Search Results” and in the “Collections” I cannot directly (!) copy a folder or text (marked folders or texts) to another folder or text in the binder or to another collection, e.g. to my “Manuscript” folder. Yes, it is possible by the workaround “Reveal in Binder”. But this procedure is extremely awkward.
Hello! This has been filed. We are working on adding a “Copy To” to the right-click menu that should help.
In the meantime it should still be possible to add the document/folder to another collection by right-clicking on it’s title in the binder and selecting “Add to Collection”. This does not create a duplicate document/folder, but adds it to the listed collection.
As for creating a duplicate to a new destination, you can try going to Options > Behaviors and selecting “Alt+dragging creates duplicates”. Selecting the document you want to copy in the editor and then alt-dragging the icon from the header bar to where you want it in the binder. This may be easier for you than “Reveal in Binder” depending on your setup.
Hope this helps!