Since we don't have a grasp at what killed the prior duo, I'd be prepared to see a fresh pair go through the same. I mean it's a gamble.
Due diligence as suggested could be in bleaching the tank and cycling it over again. But then I'm not sure at all it wasn't your water or something else that sickened them other than a pathogen.
Whether they brought the pathogen with them or it came from your tank is irrelevant. If it was it, the pathogen now lives in your tank and if it is the cause of their demise, it'll more than likely happen again.