Why are my cats so territorial?

I guess what i'm really asking is, is this normal for cats? I have two male tabby cats. They are 3 years old (from the same litter) and they are neutered. They aren't overweight but one is just built larger than the other one. The larger one is Alex and the small one is Sammy. They like to play together and will sometimes sleep near each other. They share the same food and water bowls as well. They are very attached to me, and spend very little time with my hubby (not sure why). I've noticed that when I am in my bedroom, Alex will always follow me in and try to cuddle, or lay down to take a nap. Very rarely does Sammy come in, and when he does they don't fight. Usually Sammy just sits outside the door and looks in at us. When I sit on the couch in the living room, Sammy always comes over to cuddle. If Alex tries to sit by me in the living room and he sees Sammy walk over, Alex will immediately get up and move. Sammy is also almost always in the bathroom, laying in the tub or in the sink, and anytime I put a rug in there, he pees on it. I don't really care that they are being territorial (except for that peeing thing), but i'm just wondering if its normal since i've never heard of them acting like that before. And could this lead to problems eventually?