AWS, running multiple server on the same instance for same type?

AWS said when we deploy the same type of application, it is better to deploy on the same server instances.

I am not sure if it is a best/better practise for deployment. Is there any further references for that?

http://ift.tt/1JMqLOn

Running Multiple Applications on the Same Application Server

If you have multiple applications of the same type, it is sometimes more cost-effective to run them on the same application server instances.

To run multiple applications on the same server

Add an app to the stack for each application.

Obtain a separate subdomain for each app and map the subdomains to the application server's or load balancer's IP address.

Edit each app's configuration to specify the appropriate subdomain.

For more information on how to perform these tasks, see Using Custom Domains.