Noob question about article marketing.

[Calamity]

I have been submitting articles written for my main site to article bases with something like "read the original article at www.x.com" in the resource box.

Is there any downside to this? Can i get penalized by search engines for dupes?

If yes, i guess i need to rewrite the article. But if this is the case, then why would i submit to more than one article base if i need to rewrite the article anyway? Is it because the articles might be too similar and not get approved?

What is a good software for automated article rewriting and adding to databases?

Thanks!