I have read through the following two posts.
It looks like there has been some documentation on Changes to List.Contains between Dynamo 1.x and 2.x. After reading through both post I have made no headway. I am trying to deal with a cross product and cannot seem to figure it out. Any help would be appreciated. I think I am just to close to the problem.
My Solution from Dynamo 1.x
Dynamo 2.x Change
A simple test with files if you want to try it out.