Projects are often made by multiple people. For example, I might be the lead designer for an ad, but the photographer might also want to use it in their portfolio, and the designer who did the logo design/branding could also want to use it. If all three of us are co-owners and one decides to drop it from their portfolio, the other two will still have it.
Suppose that there is a project (bottle tag) that is first designed by creative studio A and then the client wants to make more changes to the tag, so he hires creative studio B for doing those changes. Will the newly designed tag be considered to be a multiple people project?