Banned from Google and don't why?

Suddenly two sites are missing from Google

[allanp73]

I have two sites which suddenly disappeared from Google. They were on the index for almost a year and now gone and pr's are 0. I never spammed or did anything wrong with these sites. Both sites are on Yahoo and were linked on many government and educational sites. They were both on DMOZ but were strangely removed. Neither have links to bad neighborhoods or anything that would justify the removal.

I need help! Anyone have any ideas?

[allanp73]

How does Google detect dup content?
I use a common glossary on the two sites that were banned. However, this same glossary on several other sites that are in the group and these sites are fine. (keeping my fingers crossed) There was no intent to spam Google the glossary was generic information that was useful on all the sites. If this is the reason for the ban on the sites, why were the other sites not affected.
Personally, I don't believe it was the reason.
So how does Google detect the dup content? If the content is changed will Google remove the ban.

Cornwall you mentioned the shady use of hyphened names and lack of unique content. Actually the hyphened URLs were used to create a theme so the sites could form a network. As for the content each site has about 100-150 pages of content that solely appear on that particular site and it is excellent content many educational and government sites linked to it because it is useful. I wanted to address you comments because 2 years of work went into developing the content for these sites and it is annoying to hear someone dismiss it as shady and not unique.

[Good_Vibes]

This dup content theory doesn't really add up.
There are just too many good sitest hat would get nailed.

Someone has suggested that spammy niches get a different algo than non-spammy niches. Perhaps the dupes banning only occurs in spammy niches?