To configure Tomcat multi instances in Windows , you have to download this Tomcat.
Take version 8

Copy everything from the archive (for example ) to C:\tomcat\apache

In the C:\tomcat\apache create two folders “servera” and “serverb”

Now folders conf, logs, temp, webapps, work copy to
C:\tomcat\apache\ servera and C:\tomcat\apache\ serverb
and remove from C:\tomcat\apache

Now go to C:\tomcat\apache\serverb\ conf and open for editing.

All ports ( labeled as port = ****) rises to 1. Example , port = 8080 change to port = 8081

Go to the folder C:\tomcat\apache\bin
Here we have to make two copies of startup.bat: startup-a.bat and startup-b.bat

Open this 2 files and after rows
rem ---------------------------------------------- -----------------------------
rem Start script for the CATALINA Server
rem ------------------------------------------------- --------------------------

setlocal

add variables
set “CATALINA_BASE = C:\tomcat\apache\servera” – for the server a
set “CATALINA_BASE = C:\tomcat\apache\serverb” – for the server b

After this, run two of these files , and we have 2 instance.