There are some options. We need to know some additional details.
- You indicate the incoming requests are identical, except that a value in the header changes. Do you need to determine the response based upon this value in the header?
If so, you might consider using a Request Data Manager DPH to move the key/value pair from the header into the request's argument list so the VSI can include it during request comparison.
Request Data Manager Data Protocol - DevTest Solutions - 10.3 - CA Technologies Documentation
- If the header does not play a role in determining the response, then how do you know when you need to send the good response vs. the bad response.
VSIs allow the storage of more than one response to a request. You need to enable Allow Duplicate Specific Transactions option.
This will cause a round robin situation where one time the good response will be sent and the next time, the negative response is sent.
Transactions Tab for Stateless Transactions - DevTest Solutions - 10.3 - CA Technologies Documentation