Well after so much time, i think nobody is interested in answering my
question, guess its too difficult ? whatever i still dont know the
answer, but know what i am good at guessing, so here comes my guess.

To distribute load amoung the various cache engines in the farm, you
might just need to tell them that you want them to share the load, and
for that you must tell them that you want them to work as a team, ie
you will have to tell them that they are the team members, i mean you
have to peer them.

Then all cache combined will have the single cached data within their
caches combined together, no duplication.

To be precise : communication between caches ( peering ) is a must for
load distribution as i wanted.

I have not implemented this, but this might just be the key.