split test scenario against 2 hosts where one is a baseline *at the same time*

Hi,

How would I go about running a scenario against 2 systems, where the first is the running live code (baseline) and the other is hosting the feature under development?

I’d like to be able to run the scenario simultaneously to control for latency effects and present the results together from the different servers (which could be 2 ports on localhost).

Pointers to examples or documentation most welcome.

regards,
John