Thankyou for taking the trouble to look into this and sorry for not being more precise - or even accurate. When I said Google says - Google says nothing. I just assumed because I couldnt think of any other reason.
To answer the questions I should have stated:
The pages are about similar subjects, the meta tags are all different (though something like big red widget appears in two titles though not in the same place), the text on each page is unique - cant see any identical strings except for "big red widget" and "really red" - both of which are moderately competitive search terms.
When I search for specific phrases in google I get your search for "bla bla bla" did not match any documents.
Adding &filter=0 to the search query makes no difference - though loads of pages from the site returned (the phrase is in the top menu)
The url doesnt show in a site search or in webmaster tools
I dont know if the widget finishing pages ever appeared in the serps. Other pages I introduced at the same time are there.
So from what you say it looks like its not duplicate content.
But I can't believe its a supplemental results issue - the site has 7 top level menu categories. The widgets page is one of them so it has 100s of internal links and some (not many) external ones as well (ezine articles is one).
It seems unlikely that something is wrong with the site architecture/backend also, because all the other top level pages are ok and the widgets page is generated identically so I cant see how it can be that.
One other thing - dont know if it is relevant - in the Google sitelinks for this site, the other pages in the top menu get their own sitelink. Widgets are listed in the sitelinks, but the link is to the home page. The home page emphasises widgets no more than the other categories.
It isn't possible that Google has just got confused and will sort it out in time? The site only has a pr of 4 so maybe it's just not that bothered? Or are there any other possibilities?