There's no way to dynamically create or duplicate elements/symbols and insert them into Hype's runtime. You'll have to make multiple copies ahead of time - enough to make sure they don't all get used so it appears they are all new.
Of course this is something common that would be nice to for Hype .
I assume you're referring to physics bodies? If it is able to settle down, they will "sleep" but there's a lot of bouncing/falling situations where this might not be the case. You could make a timeline or animation that gets triggered at some much later point that could change it from dynamic to inactive via keyframes. There's not a way to do this from code (but we have perhaps the longest forum thread about adding a Physics API!)