In the past I’ve been able to duplicate all my recurring, non-ticketed events and just change the date. It is not allowing me to do that now, even when I set Display Ticket Selector to NO.
This part I don’t understand, that setting won’t prevent/allow you to change tickets within the event. That option tells EE if the ticket selector should display in the event on the front end.
What it sounds like is happening is your Duplicating an event and the default filters are filtering our the datetimes/tickets on that duplicate so you then can’t see them.