Can two intelligent alien races form on the same planet?

Can two intelligent alien races form on the same planet?

Can two intelligent alien races form on the same planet? That is one of the most interesting visions of the hypothetical lifeforms and intelligent aliens that are created for the SETI program. The thing is that the human race is violent species but the alien race might be more tolerant of other species. In most scenarios, the cultural evolution on the alien planet follows the rule that  "the firstborn takes everything".

But we ever thought that aliens might be tradesmen. They might exchange technology and culture in the spirit that both sides are benefiting. Maybe their way to think is not so extreme and black and white like our way to think. They might think that everything must not make themselves. 

But what if another alien race is living in oceans and others live on drylands? Those aliens would benefit each other. And they would not be competitors. 

But the fact is that there is the possibility that two intelligent alien races must start to tolerate each other and in that case, the other alien race might have food like algae. And others might handle to make things like fire. 

The thing is that in this type of symbiotic cooperation. Both of the alien races are benefiting each other. In this type of scenario, the point is that two intelligent alien species are not thinking of each other as competitors. Both of those aliens require protective suits that they can go to the other lifeforms' environment.  

For creatures that are living on drylands, the oceanic environment is hostile. And the same way the oceanic aliens would not feel comfortable on drylands. There is the possibility that in this type of scenario that the hypothetical alien races would live together. And develop their culture and technology. 

Can this thing happen in real life on some distant planet? 

The aliens that have culture are intelligent. Their culture and way to think are not probably similar to ours. So that means that there is the possibility that aliens might not always follow the rule "the firstborn takes everything".  When species are acting violently against each other, the reason for that is competition. Violent behavior guarantees respect and gives protection. 

The beasts are hunting vegetarian animals, but also vegetarian animals are using violence if they are under attack. The horns and other things are made for self-defense. The violent behave in the cases of self-defense is formed for protecting the group. The violent behave between the vegetarian animals is the result of the lack of resources. If there is not enough food for everybody, that causes the need for the fight for the food. 

The lack of food might be the reason, why two intelligent species are starting to cooperate. If there is long-term dry weather on the planet, there will be a lack of food in dry areas. But there is food in the oceans. That food is in the form of algae, and if the oceanic aliens would deliver it to the drylands aliens, that thing will make the situation easier. 

And for return services, the dryland aliens would offer the fire for the oceanic aliens. Or otherways the motion might be coming from oceanic aliens, who are offering their services for the new company. And maybe those two hypothetical aliens are going to stars someday.