Wordpress is well known for it's blogging capabilities. If one were to use wordpress to put their content, will usage of Wrdpress lowers its a advertising rate?
And why exactly should it? It just presents the content the other way. Short and sweet version of the anwer: NO!
this is what I meant. If there are two website having similar content but one is using Wordpress and the other, say, Joomla. Will wordpress make the site less valuable.
Nope, it will depend on which page ranks better. Even tho with duplicated content, the site that has the post/content made first will (or at least in a certain point of view) have more success in the SERPs if they are in the same page ranking.