Having multiple Tomcat instances on your development machine is great. Here s how I usually do it for Windows (the important parts for setup are in steps 2, 3, 4 and 5):

1. Install a copy of Tomcat 6 to a directory (like C:apache-tomcat-6.0.20).
2. Copy the conf directory to another directory (like C: omcat-1)
3. Under C: omcat-1, create a bin directory

4. In the C: omcat-1in directory, create a file called startup.bat that reads like this:

   set CATALINA_BASE=C: omcat-1

   set CATALINA_HOME=C:apache-tomcat-6.0.20

   C:apache-tomcat-6.0.20instartup.bat

5. In the C: omcat-1in directory, create a file called shutdown.bat that reads like this:

   set CATALINA_BASE=C: omcat-1

   set CATALINA_HOME=C:apache-tomcat-6.0.20

   C:apache-tomcat-6.0.20inshutdown.bat

6. OPTIONAL: create a file called setenv.bat in the C: omcat-1in directory to set any environment variables mentioned in C:apache-tomcat-6.0.20incatalina.bat. This is the place to set system properties, JPDA addresses, etc.

7. Create the logs, temp, webapps and work directories under C: omcat-1
8. From the C: omcat-1 directory, run binstartup.bat
9. Repeat for your other installs from step 2 for as many tomcat instances as you need.

Try not to install Tomcat in a directory that has spaces in its name. It should work, but you ll experience fewer problems that way. I do not know how this would work if you were using the "tomcat as a service" option for Windows.

From here, you should be able to isolate tomcat instances. Just be sure to edit your confserver.xml file so that the shutdown ports and HTTP connector ports don t interfere with other Tomcat instances that may be running. I usually assign values like 8005, 8006, 8007, etc. for the shutdown port and 8080, 8081, 8082, etc. for the HTTP connector port.

There is an easier way. Simply don t define the CATALINA_HOME as a Environment variable on your machine. startup.bat and shutdown.bat already come with the following code:

if not "%CATALINA_HOME%" == "" goto gotHome
set "CATALINA_HOME=%CURRENT_DIR%"

You should be all set. PS: Remember to edit server.xml and put a new port number though. :)

This link has an answer that worked well for me. One thing some of the other answers seems to ignore is that there are multiple places in the server.xml file that must be modified. Before stumbling on this answer mu tomcat servers were competing with each other for certain ports. I had changed the HTTP/1.1 connector port to 8081, but neglected to change some other ports that apparently mattered for my tomcat (version 7). FWIW I had one tomcat service version and one non-service version.

First server.xml file

<connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />
<server port="8005" shutdown="SHUTDOWN"/>
<connector port="8009" protocol="AJP/1.3" redirectPort="8443" />
<connector port="8100" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />

Second server.xml file

<connector port="8081" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />
<server port="8006" shutdown="SHUTDOWN"/>
<connector port="8010" protocol="AJP/1.3" redirectPort="8443" />
<connector port="8101" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />

http://www.ansoncheunghk.info/article/5-steps-install-multiple-apache-tomcat-instance-windows