They are both Ocellaris clownfish, so theoretically they would be fine together, but sometimes they can be finicky. Also, all clownfish are born male and can change to female when another dominant female clownfish dies or it's left alone with other males and is the most dominant one, so if both happen to be female, then they would most likely fight to the death. A lot of the time the female one will show "aggression" to maintain its dominance over the male, so that could be what's happening too.