It sounds pretty normal to me! In fact, it probably means that you have a strong bond with both your children.
Becoming angry with the younger child will only make matters worse. After all, he's concerned that he won't get the affection from you that he craves because you'll give it to his big brother. The only way to show him that isn't true is by doing two things:
1. Stop him from attacking his big brother by keeping them apart when the older one is showing you his affection.
2. Give the younger one some affection at the same time.
In other words, when they're both in the room, hug one in each arm. It also helps if you spend at least a few minutes every day alone with each of your children so that they can have your attention all to themselves.
Once your younger child feels that you'll always be there for him, he'll stop being jealous.
