Unable to set endpoint separately for two REST request steps

I have a need of setting different endpoints for two REST steps of a test case. 

I am using below groovy in setup script of Test case: 

testRunner.testCase.getTestStepByName("http_request_200").getTestRequest().setEndpoint("https://secondendpoint/v2")
}

Issue: This is setting up "https://firstendpoint/v2" endpoint for entire service profile and hence all other requests will run with this. 

Requirement: "https://secondendpoint/v2"  should be set only for "http_request_200" and all other requests should run with default endpoint ( "https://secondendpoint/v2" )  which is set for the service in Environments window.