When splitting the topology is necessary or desired, you can install multiple IP Managers on a single platform. There are some caveats to this approach:
The platform must have enough memory to meet the requirements for all of the IP Managers.
The platform must meet the minimum polling requirements for all of the IP Managers.
Discovery time may be impacted by the overlap of discovery tasks as the discovery threads compete for CPUs. Even if you plan for CPUs for discovery threads per IP Manager, one IP Manager may end up trying to use more than its share, and thus impact the other IP Managers.