I think you need to better explain the issue.
if you monitor the same set of VMs from 2 agents on 2 different hosts, then you may get double monitoring, that is true.
it's not clear though, why you have 2 agents monitoring the same to begin with.
it's possible you may get better result if you monitor based on ESXi connection and not the vCentre one.
VSM KM support both methods of monitoring of course.