For some reason, when using features to add pages to a WCM site the webparts that exist on the page appear duplicated.
But using API and getting the object weparts using the GetLimitedWebPartManager there is only the correct webpart.
Then when i was trying to find the reason for this problem, the SharePoint Designer gave me the solution.
He automatically added to the <%@ Page this information meta:webpartpageexpansion="full".
So i've changed the page on my feature, deleted the page from my site, deactivate the feature, activate the feature and voiala my page is working.
By the way i've used a feature to add pages to my site because the page will exist on every sites and subsites of my site.
CHANGED: Don't use this option, please see the comment to this post
