In response to query "And my intentions is to know, do we need to enable the default agents in both the nodes? Or we can run the agents on only one node as we run the our own agents in one node?"
Ideally in multi node environment connected to LB, it's advised to have the similar configuration across all nodes. Consider the situation wherein the only one configured node is down (may be any "x" reason) and the need to run the agents are on priority, how would you fulfil this on priority specially in production emergency situation?
No it is not necessary to have all default agents running in Production and ideally you should not have.
Also in a multinode environment with batch processing its highly likely you will have two types of nodes, those handling end user requests which will be load balanced, but there could be another n nodes running batch processes via agents. You would only have the batch agents running on designted batch nodes not all nodes.
In some instances Agents can only run on one node, this may be due to design if custom. Although not ideal we have this with ADM in the decisioning area.
OOTB agents should be altered in different environments, what you have running in Dev is not the same as what you want in Test or Production.
Also the schedules should be altered as they are too frequent as provided OOTB and depending on your applications and end user base may need to be altered for when they run so that they do not impact end users.
considering a production system the following agents may need to be switched off (disabled so they dont appear in SMA or AES)
GenerateStartingflows not in production
those in PegaAESRemote if your not using AES
PropertyOptimisation yes in dev not in upper and prod environments
Refactor Copy/Move/Merge yes in dev not suitable in prod and higher environments
UpdateActiveNonQuiesceAdmnRequestors remove if not using HA clustering
PMF items remove if PMF is not used
Decisioning items remove if decisioning is not used
pycleanUpSSOn if your not using get rid!
dare say theres a few othes too, you need to determine what your using where