what the turkeys you saw were doing was actually what is called PUTTING,it's their way of telling others something isn't right.....a cluck is different , the clucking and purring you heard the second time was probably them just feeding by, they cluck and purr when they are relaxed, it's a way of communicationor when they are getting aggressive(which in that case is louder).....you'll be able to tell what they're saying before long, you just have to spend time in the woods learning and watching....