Obsession
Which West Terrace tile should I use and how many copies of a tile are allowed?
Use the original second-edition West Terrace the game was designed around; the replacement is an option, and the base game has one tile with Upstairs, Downstairs adding a second. As a rule of thumb, never put more than two of any tile in the game, other than START tiles. Extra copies from expansions mostly replace first-edition tiles.