Multiple messages to the same Saga

[ThreePinkApples]

I tried to write a test today that sends multiple messages that will trigger the same Saga.
Using ExecuteAndWaitForSagaCompletion does not work in this case as it only checks for the typeof(TSaga) without the ability to do any further mapping. And the ExecuteAndWait method is private so I can't write my own version of ExecuteAndWaitForSagaCompletion.

Is there any other way of handling this? (other than doing it sequentially)