How do deploy two alfresco war within same tomcat instance? I am able to run two tomcate instance within same machine and it work but now I want to deploy two alfreco war within same tomcat , one is alfresco and second is alfresco1 so that i can use it by using url http://localhost:8080/alfresco and http://localhost:8080/alfresco1
Slightly longer answer: you could but you'd have to modify quite a few things. For instance the RMI instance for the second install would need to run on a different port and would need to be modified to bind to the correct URL. You'd also need to make sure that any references that included urls were modified for the second instance (they should all be relative).
Alternatively why don't you use Alfresco's multi tenancy feature to run different customers on one instance. It would make support much easier than running two separate instances. Check out further details at http://wiki.alfresco.com/wiki/MT.