I tried to book a double room but it was not possible, the rooms are only given when you arrive. But I was lucky, when I arrived a double room was available. The owner was very helpful and gave me interesting information about several activities in and around Ushuaia, as well as some advice for bars and restaurants.
The only thing that I found strange was that I was unable to lock my room, there were no keys. This meant that I always had to carry my valuables with me, which I found quite a nuisance.
Apart from that, my stay was ok.