How many examples do you have in total? If you have several users accessing the same URL and app, it can happen that the app has already requested the next batch of data for one use Examples are loaded in batches (by default, 10) and if the queue is runnig low, the app will fetch more in the background to make sure you're never running out of tasks.
As a quick fix, try setting "batch_size": 1 in your prodigy.json or recipe config. This will only ever fetch one examples from the server and should reduce overlap when several requests are made.
In some cases, it can be better to start separate processes, one for each user, and use a custom recipe to decide which examples to send out to which user. I've outlined an approach for this in my post here:
You might also want to check out this great community add-on: