I doubt the FP (fake patient) will notice the difference, but just in case you need to differentiate between a diastolic murmer or an S3,S4, or gallop, bring a dual faced stethescope....btw, I don't think you'll need to worry about this, but hey, why not be on the safe side and try to impress them, huh? Afterall, this is simply an exercise of good acting (on both ends).
Good luck.