Hello Bonsky
There is absolutely no problem in having 2 versions of java
The base version V1.1.8 will get installed in /usr/jdk_base directory and the V1.3.1 will get installed in /usr/java131 directory.
So when u want to compile your code with 118 you need to have your PATH Variable , LIB Variable , INCLUDE variables set to V118 path in your .profile file
When u want 131 u need to set it to 131 Dir in your .profile file which resides in your Home Dirctory
I am currently having 2 versions and it is working fine
Cheers
Naveen