Similar thing happened here at a big shopping mall. All the fire sprinklers where the wrong type, and all the pipes and sprinklers had to be changed. This was discovered a week before opening. Was delayed for months, because most of the pipes where embedded in concrete. Stuff like that is more common than you would think. Sometimes the equipment specified in plans can't be obtained, so they switch to a different brand or slightly different type, and then it turns out that it does not meet the requirements set. Usually that is not a major issue, but with safety systems, it must meet minimum specifications.