Questions regarding my dog's poop and pooping habits.?

Hi, I have two male queensland healers. One is almost nine months old the other is almost thirteen years old. Both pets do their business in my side yard which is gr and this is where I want them to do their business. The older one poops once or twice a day. His poop is solid and about enough to fill the palm of my hand. When he squats he stays put until he is done. later in the day he will do likewise just in a different area in the side yard. This is all fine. What I am curious about is why the poops from the younger one are always soft and a little smaller. In addition to this he does two other things when pooping. After the soft poops come out, he then poops these numerous, little, really mushy poops and unlike my older dog that squats in one area until finished the younger one insists on doing his business in two or three different spots in my side yard. In short, I would like his poops to be solid and in one spot. Any suggestions? Thanx, Bob