@Shashi_Mulugu
Replication agents are central to Adobe Experience Manager (AEM) as the mechanism used to:
1. Publish (activate) content from an author to a publish environment.
2. Explicitly flush content from the Dispatcher cache.
3. Return user input (for example, form input) from the publish environment to the author's environment (under control of the author's environment).
Even if you have multiple publishers, multiple replication agents would be on the Author.
Kautuk Sahni