Hey Richard,
Thanks for reaching out to us!
I’m not sure I’m following exactly what you’re looking for but I’ll try to answer as best as I can. In any environment, there is only one calendar per site. If you have a multisite install, each site within the network will have it’s own calendar.
The calendars are not user specific though. You could mimic some of that by taking advantage of the event categories. You could then do some custom development to have an event category associated with all the users that would be able to create events into their “own” calendar.
Let me know if this helps.
Thanks!