The same configurations to both servers are not always mean the same usage of memory in clusting.It also infected by the client requests each web server serves.
And in clusting,the requests each worker node serves are defined by the "lbfactor" directive,see below:
# Define Node1 worker.node1.port=8009 worker.node1.host=192.168.10.128 worker.node1.type=ajp13 worker.node1.lbfactor=1 # Define Node2 worker.node2.port=8009 worker.node2.host= 192.168.10.129 worker.node2.type=ajp13 worker.node2.lbfactor=3
As you can see as above,the node2(lbfactor=3) will serve three times requests more than the node1(lbfactor=1).In this situation,the memory usage of node2 maybe more than node1 depends your app.
Hope this will help you.