Yes, it is normal. The fighting can get intense sometimes. My male maroon had almost all of his fins chewed off by the female. For a few days she kept him in a corner, behind a sponge filter in my QT, and would not let him out. I was quite concerned. Then at feeding time, while she was off getting food, he would dart up quickly to grab some then go back to his hiding spot. When I noticed this I started adding some food to the other side of the tank first. When she swam away to eat over there, I fed the smaller male over his spot so he didn't risk being disciplined by the larger female. It worked well. The fighting lasted for several weeks. Gradually she let him come back out again. I dosed the foods with a rotation of Vitachem and Zoecon to keep his immune system up. All of his fins grew back. There are some cases where the dominate clown will pick on the other until it dies. It helps to have one clown larger than the other and to boost their immune system as much as possible. To do that you will need to feed them a high quality diet, dosed in vitamins, and keep the water parameters ideal.
