Once you select a combat style as a 2nd level ranger, you can no longer select the feats that you are granted by that style. For example if you make a 2nd level ranger with two weapon style 4th level fighter, you can not select improved two weapon fighting as a feat. All of the prereqs are met, but the feat no longer even shows up on the selection list. This goes for greater two weapon fighting and the archery granted feats as well, if you take archery style.