Do you mean a two story hutch for them to share or two seperate hutches one on top of the other?
I think "Thistle Hall" from pets @ home is around £120 and is a two story single hutch that is a nice size. I haven't used this one myself.
There is a similar but slightly smaller design from Jollyes for around £80 which I have myself and although it is quite well made, I am slightly annoyed that half of the upstairs does not open out and so you have to reach your arm around from the sleeping area to get in there. Quite hard to get a rabbit who is trying to get away from your out.