In Shutter Island (2010) there is a lighthouse. Although the location of the exterior is explained in standard movie location websites, I could not find an explanation for the interior having an elaborate wrought iron spiral staircase. I ask because this staircase seems to be very similar to the staircase in another movie, The Lighthouse (2019), starring William Dafoe. However, my understanding is that the lighthouse in that movie was constructed especially for it.
So, is the resemblance between the staircases coincidental or are they connected in some way?