Fights between siblings is a normal happening. Starting from the fight over the television remote, jealous of his brother getting more ice cream, or annoyed at the younger brother of shoes littering, and much more.
However, it is in fact indicated a sense of mutual affection are reflected through the opposite behavior. Do not equate disputes between siblings as a signal of hatred. Try it back to yourself, you are not likely to start a fight on the person you do not feel close and familiar, does not it? The same thing also happened on the mindset of a child, without them knowing they know that the brother or sister will always be there and will not leave them alone.
Rather than rush to separate siblings, parents play a better brain to pick toys that are not too competitive and can be enjoyed together. Therefore, although often times end up fighting, brother-sister love to play together better than they are playing apart.