Currently a component is fully chained to the original document it was built in. No way of copying the component will unchain it from that source document unless the component is unlinked and rebuilt from the ground up. Given that early mock ups or sometimes separate documents are where an idea may be built then brought in later, this creates a chaotic hop around from source to source to source. As far as I know, there's no way to reliably drop all source elements into a single document after the thing has been built.