So, before posting your articles to another website, at first add on your own website and wait until Google your article. Google will consider your articles as a original contents of your site if they get the article on you site at first. Then if Google too find the same articles on other websites, that'll be duplicate contents of you site. If Google gets any new contents in a particular website, it's marked as original contents of that site others will be duplicate.
Until it works I don`t care , I don`t want to spent so much time than you to do everyting manually, how many customers you have ? Manual working is good for someone who has one or twoo sites, if you have them >50 you don`t have a time for manual submissions. I have better ideas to spent free time than hand working. Yeah it`s a PHP script ,It runs every 2 mins from cron for 24 hours/day, I have aprox 100 websites running in this, do it for aprox 200-250 phrases ,most part of them are inside an articles. This script is a fully automated , auto submitter to the directory and article directories , works perfect. Every day I adding to the existing articles some fresh content (new section) and system cares to rotate it with each other sections of the article. I didn`t say it is a still same content, it`s growing (but still related to the anchors I put inside) , when script runs it add to the wordpress only 5 random sections with max 3 links inside, and randomly uses a synonyms for other words i defined. Each section of article is an related to each other and coud easily exist separately if I want. I write fresh content to one article in small 400-500 characters long sections, paragraph has only one anchor and many synonyms for other words. In an article aren`t more than 3 links ,script automaticaly cares about it. Works perfect and saving much time.
Could you please provide any related reading to this topic as how many text we need to change in order for google not to treat it as a dup?
Sounds about as good as a doorway maker. You are one of the reasons why the Internet has become a cesspool of unintelligible garbage. I have seen these types of pages, and if it is anything like what you just spewed out above ... the articles are unreadable trash. What do you think you can gain from any page of this type? Readers? I doubt it. One look at the page, and they click away.
I have 50+ domains. All original content. All done manually and all loved by Google Yahoo & MSN. Very rarely need to update due to the SEO work done. Care to post how much your automatic junk has earned you so far? And please no BS posts as we can all see through the smoke...