"Dune: Part Three" and "Avengers: Doomsday" are opening in theaters on the same day (December 18)

Why Are ‘Dune: Part Three’ and ‘Avengers: Doomsday’ Opening in Theaters on the Same Day?

Why are "Avengers: Doomsday" and "Dune 3" coming out on the same day? And will either one move?