Aren't PPBs host broadcasted by, say, the BBC - and ITV or vice-versa has to opt in to a dirty feed of the rival network to play it?
That ceased in the 80s ( and there was a instance of a BBC continuity announcer’s voice accidentally going out on ITV !)
Even if there was the requirement for a live ( or recorded) simulcast today, the ‘other’ broadcaster(s) would almost certainly be supplied with a clean feed.
BTW there is no such word as ‘broadcasted’. The word in all tenses is ‘broadcast’. Just saying.