I first read it incorrectly and assumed the batch hash was the hash of the next server seed, which is not the case.
Why did you take this approach instead of just publishing the hash of the next seed?
Do you mean kind of the server seed that changes, say, once a day and its hash published somewhere on the site?
Well, with this I should also make sure that you cannot use client seed twice, since it will be obviously exploitable, so I just thought making unique random seed for each bet would be more secure, the problem was that publishing hash of this seed wouldn't make much sense because it would always change with each bet, so I decided to combine them in batches and publish the hash of the batch.