Is duplicate content ...

I requested a reconsideration request for a deindexed site of mine. G answer was " bla bla bla bla bla bla quality guidelines bla bla bla quality guidelines".
Then I checked my site with copyscape and it appeared that there are some duplicated content on other sites. But it is duplicated back in the time so until the penalty it seems it was not a big problem.

So my question now is - is it now this content problem and because of this G team rejected my request ?

The Panda update has really cracked down on duplicate content, so if I understand your post correctly, having duplicate content would penalize your site.

how about duplicate content on your own website across multiple pages but with slightly different titles and a few words changed in opening paragraph?

dvega said:

how about duplicate content on your own website across multiple pages but with slightly different titles and a few words changed in opening paragraph?

Click to expand...

No, I don't mean that. Seems that some sites have copied content from me some time back in the year.

I don't think it is duplicate content if it is the case then check this tread
did you checked your sites back link if it is form a porn site or any other malicious site . check for your neighborhood website if it is malicious .
also check if there is any problem with your robot.txt and site map

read this for more info I had my site got deindexed and robot.txt was unreachabel and finally fixed my site was having a bad neighborhood website .

you could check this blog for more help