I would write just one article.

If you write 4 articles competing for the same keyword the link juice will by divided by four

I did the same mistake in the past and as a result google was not really sure which url should rank for that specific keyword

Hope this helps

I have the same problem, sometimes i optimize the metadescription to increase my CTR but google doesn´t want to show it.. grr

As Alick300 told you, it´s better to have link from multiple domains!

But if you have 2 backlinks from the same domain, as soon as they are contextual and not located in a sidebar/footer etc.., they will for sure count. Sometimes i even notice that the 2nd link was giving me even more strength than the first one

If i can control where to place the links in a specific domain, i usually generate between 2/3 ( different urls ), but not more :-). This definetly works for me.

Br

//Oliver