Hi! Are you using the latest version of Prodigy v1.11.7? We recently shipped a fix for a problem that could cause duplicate batches to be sent out to different annotators under certain configurations.
Another thing to keep an eye out for in your multi-annotator setup is whether you end up in scenario where annotators stop working before submitting their annotations and triggering the "work stealing" mechanism. If an annotator requests a batch but doesn't annotate it for a longer period of time (e.g. if they just close the app) it will eventually be sent out again to the next available annotator, to make sure you don't end up losing a batch if an annotator doesn't annotate it.