overrideHostUrl in scripts

Hello guys,
I am trying to use a SCRIPT via webpagetest.org that has something like this:

overrideHostUrl site-one.com site-two.com
navigate http://some-site.com/


After the test finishes I was expecting to see in the waterfall all the requests to site-one.com being replaced with requests to site-two.com, however the requests are still sent to site-one.com.

Am I doing something wrong or my expectations are incorrect or there is something else that should be added to SCRIPT to make it work?