I have tested the scenario that you have described in Firefox with version 2014.2 724 and everything is working correctly on my end. I have also changed the culture to "ru-RU", but again, the dates are correct.
Can you please test our online demo and see if you can replicate the same behavior:
If the issue is not replicated in our demo, please upgrade to our latest version and see if the problem in your local project will be resolved.
I am looking forward to your reply.
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