Free night in hotel?

We arrived yesterday at 23:30 to Kazan in Tartastan republic. While looking for hotel, at one place they say they were full (but we did not believe), second place the room was too expensive for us and third place, already at 00:20, they had a room, bit expensive, but we accepted.

Everywhere in the papers they put we check-in the 10.June and checkout 11.June. This morning after breakfast we went to tell we want to stay one more night. They told that it is already registered that information… So we think that they think we just arrived and we did not sleep already one night there.

Lets see tomorrow when we do the checkout if they ask for something. Anyway we know that because of this, for sure today we did not get our room cleaned.