Sure, you
can run multiple instances of Tomcat (they'd need to use different ports, though - you can only have a single instance listen on port 8080). But the URL structure you posted seems to indicate that running 5 web apps on the same server would do just as well.
There are other options, too. You can have a single Tomcat instance that runs 5
servlet containers on different ports. Check the Tomcat docs for details.
But what do you mean by "crash"? Why would a Tomcat instance crash - for internal or external reasons? If the 5 web apps all do the same thing, I'd rather run a single instance and set up monitoring tools that restart the server if it goes down.