With a single license, multiple instances of Composer can be run on the same PC at the same time. As a result, more than one experience can be edited at the same time and content can be copy and pasted between them.
Due to advanced capabilities like binding and remote actions, the algorithms used by IntuiFace to paste copied items can be quite complex. Luckily, all of this happens under the covers so it should all work seamlessly. For example, if your space references an interface asset, the copy/paste of that space will also copy over the interface asset as well even though, technically, the interface asset is independent of the copied space.
The only known copy/paste limitation between two (or more) instances of Composer concerns triggers and actions. Triggers and/or actions cannot be copied and pasted independent of the item (e.g. asset or colleection) with which they are associated.