No. They aren't all from the same code base.
Interestingly, at least two of them are ColdFusion based: the Windermere one and the homes.com one. The URL schema is very different, though. I think the homes.com one may be using a ColdFusion framework (Fusebox?), but maybe the Windermere one is not.
In contrast the movoto.com site uses ASP.NET (.aspx), as is sawbuck.com. They're very different from each other, structure-wise.
I could not determine (quickly) what Estately is using. FWIW, I thought their site was more polished and quite modern in comparison to the others.
If there is a common thread, it's the data. There are a number of APIs they could be using that are common, despite the lack of commonality in the programming. Here is a site that lists web API available for consumption: