Hi Sandeep.
In short, no.
While you can have multiple versions of DB2 installed at the same time (/opt/IBM/db2/v8 and /opt/IBM/db2/v9) CMOD doesn't support this by default. Additionally, different versions of DB2 require their own databases, as there are modifications to the database format between versions. A similar problem exists for CMOD if you're using substantially different versions where changes were made to the system log or CMOD's internal tables.
There's also a drastically increased potential for human error -- if the wrong command is run on the wrong version of CMOD against the wrong DB2 instance, you can mangle the database or cache filesystems associated with it.
Your best bet is to use virtual machines (CMOD on Linux running in a VM on a PC) or Logical Partitions (LPARs on AIX).
-JD.