I've checked, there's no mention of idempotency in the [`RequestSpotInstance`](http://docs.aws.amazon.com/AWSEC2/latest/APIReference/ApiReference-query-RequestSpotInstances.html) method in the REST API (not just the Java SDK). I've looked through the parameters and nothing seems to emulate it, `ClientToken` or anything else.

On the other hand, the RunInstances requests (for on demand or spot instances) aren't looped or retried in the process. I see that the process ID is the `ClientToken`, isn't a new process ID generated for each create call?