An intersection node on the same family type, in a single list

How to create an intersection node on the same type of family, in a single list?
Usually it takes 2 input lists to make an interference.

Hi @Alain_Hamel

Thank you for your answer, but I think my explanation is not clear.
I take this opportunity to modify the data to simplify the reflection.

  1. I have a list of walls (A)
  2. The list (B) of the opening in the walls (A) - identical order

I would like to find the conflict between opening.
For simplicity, I thought comparing the list of walls to find duplicates. Indeed, if I have several times the same (ID) in list (A), there is more than one opening.
3) Create a new reservation list (only one with a common wall)
4) Find conflicts . the problem is that I only have a list!

I found a solution. (Not the simplest)