[Critter]

I have a 13 months old and 6 month old yorkie. I started to notice that the 6 month old one marks wherever the older one pees now (who is completely housebroken so it isn't happening in the house). Can dogs just have this marking behavior outside but never bring it inside? Both are neutered but we have had a dominance issue with the younger one from the day we brought him home and he only weighed 1.8 lbs then and knew he was going to be the alpha male. I don't mind this behavior outside I just don't want him doing it inside.