Want to know about duplicate contents and how can we recognize them. Are they have any concern with the linkbuilding? Please explain.
duplicate content is problem if you are trying to get ranked with itr on your site though you wont get hurt if you get linked from duplicate content pages the reason people spin articles is to make it look unique so it gets accepted in the article dirs, it has nothing to do with duplicate content penalization
copy scape is a best to detect duplicate content, If you need well rank in search engine with competitive keywords for long time then avoid duplicate content at your website.
Yes copyscape is the best tool to chech duplicate content or you can also check it by manually. Just copy the few text and search it in Google.
