You can install 1 agent on same machine on the same machine as the RPT workbench since an agent involves installing a service called majordomo.
The agent can be 32 or 64 bit doesn't matter.
With some clever location definitions on the RPT workbench machine you can define an agent with hostname of "localhost" and another location of the machine's ip address or short or fully qualified hostname and each use of the location will spawn a separate playback engine.
You'd still have the agent and the RPT workbench competing for the same host resources like memory and CPU but that happens anyway when you run a test standalone or a schedule with "Run on local computer".
Advantage of an agent on same machine is you can configure it's max memory size and other vmargs
#RationalPerformanceTester#Support#SupportMigration