I know you can export and import a content type between apps. But how can I duplicate a content type? If they have similar fields (title, content, link, etc), having to enter them all again seems like a waste of time.
So there is no automatic way. If you do this a lot, there's a big chance you're doing something wrong (DRY - don't repeat yourself).
But: if for whatever reason you need to do it, here's a quick checklist