This technique is accomplished by using the Allow Duplicate Response check box. But, you need to modify your VSI to accomplish this task.
1) Go into the VSI and select the operation on which you want to allow duplicate responses. Check the Allow Duplicate Transactions box in the Transaction Basics screen.
2) Now you need to create two specific transactions that are identical. Select the transaction that contains Response 1 of 2 and 2 of 2. RIGHT CLICK and copy/paste this transaction to create a new entry.
3) Now you should see two transactions that are identical. At this point, both have Response 1 of 2 and 2 of 2. In the second transaction, delete (remove) Response 1 of 2. This action leaves the 2nd response in this specific transaction.
4) Navigate to the first response and remove Response 2 of 2 which leaves only the first response.
5) Save the VSI and deploy the model.
Now, you have two specific transactions, and the Allow Duplicate specific transactions checkbox drives the behavior. The first time the service matches, the first response is sent. The second call to the service results in the second response. The third call results in the first response. The process repeats over and over. If you want to "reset" so the initial call responds from the first response, stop/start/deploy the service or stop/start the VSE. These are the only actions that 'reset' the response order.
You may want to alter your META response to contain a different response so the consumer does not get confused when sending all other requests.