Hey Lionel,
Thanks for reaching out!
These are two separate tasks with different ranges of possibilities. For the first task, which is simply to duplicate the content of Site A to Site B, this can be done rather easily using the built-in WordPress export tools. Check out this handy guide on our knowledgebase to learn how! ? https://theeventscalendar.com/knowledgebase/using-wordpress-export-tools-to-migrate-events-content/
Now, the second task you mention is keeping them in sync going forward. So while doing the one-time duplication above is easy, this continuous syncing is a bit trickier.
At this time, the only solution we have for continuous syncing of calendars is our premium add-on, iCal Importer. You can simply go to Site B and install iCal Importer on it—you do NOT need to install it on Site A. On Site B, you then just have it auto-import the events from Site A’s events feed, and they’ll stay in sync! Learn more here → https://theeventscalendar.com/product/ical-importer/
There may be other importer plugins that do this out there, but I do not know of any.
I hope this information helps!
George