So you'd probably need the "not available, but already 'stolen' case". For example, the current machine could look for work to steal itself. But this probably will increase latency a lot, so it would only make sense if the batches are huge.
The problem with the "already scheduled" pattern is when the machine holding the task falls over.
Not a good choice for bank transactions. A good option for something like a distributed build farm - it doesn't matter hugely if you compile some piece of program repeatedly, but it matters a lot if you send the only copy of some source to a machine that immediately goes offline.
Mainly bringing it up as a case in which RPC works beautifully - remote machine failures can be completely hidden by a willingness to do the work locally instead.
But exactly once processing is viable.
With Differential, the implementation does allow for idempotency in cases where you need exactly-once processing. And it does handle the "not available, but already 'stolen' case".
Disclaimer: I'm an author.