This happens on all difficulties and routes. It's activated if you Give Up and Retry on any stage 2 or 3. Any run after that will internally act as if you took the next route over; in this case, A2 becomes B1. This will make replays act as if you took the other route and make them crash, will give you the other route's ending if you clear, and most importantly, will register a clear as you having done the other route. The more you Give Up and Retry without going to the main menu, the further down the route chain it'll go (A1-A2-B1-B2-C1-C2) and after C2 it'll crash and stuff.