Robert_Charlton - 3:43 pm on Jun 24, 2012 (gmt 0)
Ummm... google is messed up?
NO! The consecutive display of up to two places from the same host (subdomain) in Google has long been a completely expected and normal behavior. If you achieved two ranking positions on a given serps page, Google has traditionally moved the second result up to immediately follow the first. They've called this effect "host crowding", and it's less technically been called "clustering".
The specifics of this "clustering" effect depend on how many results per serps page you display. If you show 10 results per page, and the first ranked at #5, then a second result from the same domain, if it were as high as #10, would move up to the #6 position... just as described here.
A second result that was #11, though, wouldn't (in this case) be moved up to #6. If you displayed more than ten results per page, though, say 20, a #11 result would move up to #6. If the second result were #97 and you were displaying 100 results per page, then the second result would also be moved up to #6.
The second result has generally been indented. The two results, with the second result indented, are quite eye-catching, and I've considered them desirable results and purposely target them when I can. We've discussed the effect here numerous times. Here's a thread that popped up when I checked via site search...
Any traffic increase with regular and indented result?
For a number of reasons, and in a number of ways, this effect has been modified over the years, but the two results is still quite normal for many results. Google has played with indent vs no indent, eg. Sitelinks of various kinds are not exactly the same thing, though other types of multiple results have been modifications of host crowding.
Most recently, Google has made a radical departure from the two-page limit of host crowding, and in some niches might be displaying a great many pages from a site for a given query. This effect is attributed to what is loosely being described as "brand authority". This is what's being discussed in the thread that Planet 13 references....
Host Crowding vs Brand Authority
I also suggest viewing the Matt Cutts video mentioned in that discussion...
How does Google decide when to display multiple results from the same website?
Matt Cutts - June 11, 2012