I agree with Jean - at this point, it's not your problem and it's probably inappropriate for you to act like it's your problem.
If, during the interview, they say, "We see you worked at X Co - we hired someone else who used to work there. Do you know Sally?", you can pleasantly say, "Not well, but yes, I've worked with her," (or, if you want to send a message, "Yes, I've had to work with her,") but otherwise let it go.
Any normal company isn't going to assume that two people have the same work ethic just because they worked at the same company for a while several years ago - and if they do, they're probably crazy enough that you wouldn't want to work there.