Not sure who told you that Creatine should not be taken with protein but if you look at where Creatine comes from, it really makes no sense at all.
Anyways, to answer your question about whether or not you have to take 2 shakes post workout: unless you can find a supplement that includes a proper amount of dextrose as well as creatine combined with the proper amount of protein needed for after your workouts then your gonna have to take 2 drinks post workout (to my knowledge no company has made such a product that I just mentioned).
My advice would be this. Post workout your first drink is 2-3 scoops of SportLab PlasmaVol mixed with 500 ml's (2 cups) of water. PlasmaVol contains Dextrose, Creatine, L-Glutamine & ALA. Plus, the stuff tastes amazing. Very easy to drink and doesnt fill you up which is very important because 5 mintues after this you are going to need to drink a whey protein shake. SportLab, as well as a host of other quality companies, make a great Whey Protein so its tough to go wrong as far as your second post workout drink goes.
Find these products here: www.directconnectnutrition.com