Vimeo is a video sharing service that works for both embedding and downloading but it is not the same type of discovery community.
Facebook was about pushing out your friend's activity to see what they were doing while MySpace was much more about posting your own and letting people click in.
Thus neither was the second, they were an evolution of a similar base into something better.
I didn't need another place to rent movies from but I did need a way to rent them without having to go to a separate store. That innovation made Redbox hugely successful, at least for a time.
When you say clone it implies a copy and that's what you see when you look at "clone" scripts -- near identical applications that seek to imitate rather than advance. That's a recipe for failure 9 out of 10, or even 99 out of 100 times. However when you say something like expansion of the concept, well that's where success comes from.
The distinct is seemingly minor but critical. Don't copy what someone else is doing; see what their users, and users in general, want to be able to do and deliver that.