That's uh.. not actually...
Some classes let you take another bonus feat if you already have the one the class is giving you? Like Marshal, and Skill Focus (Diplomacy)?
You appear to be confusing that rule, and the rule (all in the texts of the specific entries) where if you already have Evasion and a class gives you Evasion you get Improved Evasion instead, with the Dodge feat and the Uncanny Dodge class ability?
Unless it specifically says so in the entry, you don't get anything special for getting something twice.
That said, there's nothing wrong with giving someone something extra if they get the same feature twice from two classes. A feat sounds fine.
EDIT: And to confirm, if you take or get the Dodge feat twice, it doesn't turn into Uncanny Dodge. They are two very separate things.