There’s a tool for removing duplicates; it’s documented in the Screen Options on the Locations page. That’s a better way of removing duplicates, because it updates any events that have the removed duplicates to set their location to the version you retain.
The tickets link doesn’t have any awareness of whether or not tickets are currently available for sale; it’s just a generic link to how that venue handles ticketing. You’d probably be better off adding ticket sales links in events at the location, when those events have sales available, given what you describe.