what is the OS of yr machine ?
if u have AIX machine, u can use alt_disk_insatll to install/clone yr operating system, then u can install another version on DB2
OR u may make system backup of yr current system, then make fresh install of OS and DB2
if u have linux, u may have may versions of linux on the same machine too by creating disk partion and install linux over it and boot from this new linux version , then install another version of DB2
In short, i donot think that it is possible to have different verions of DB2 on the same verion of the operating system , anyone correct me if i am wong