Went to Berlin with a friend and used this place, the double was 2 singles pushed together and that seemed to be the norm.
The room was very basic and not the cleanest. Appliances and furniture were all dated and there were staines on them. Which is to be expected I guess. If I had to book this trip again on the same budget I’d probably look elsewhere a little closer to Berlin as if you want to go out into Berlin for a few drinks it will cost you a few £’s in taxis.