Not an airbus pilot, but i'm guessing a worse scenario than an engine fire is if the other completely and utterly seizes. An engine on fire still provides thrust (afterall its the casing around the engine that's on fire, the actual combustion chamber itself is meant to be on fire at all times), whereas a seized engine doesn't.
But lets be fair this scenario is so unlikely that it's nearly not worth training for. Any training you do for this could almost be considered negative training.