PF - Fighter Retraining and other classes

[Hytheter]

Ok, so Fighters are able to retrain their bonus feats at later levels.

But...

If I select a feat as a Fighter Bonus Feat, then later gain that Feat as a Bonus Feat from another class, can I later retrain the fighter feat into something else but still keep the feat?
What if that feat is being used as a pre-requisite?

The specific case is this: 4th Level Duelist Grants Combat Reflexes. I already have Combat Reflexes as a Fighter Feat. Can I, at the next even numbered Fighter level swap the Fighter instance of Combat Reflexes out for a new feat while retaining it from Duelist?

Also, I'm doubtful of this, but could it be used to trade out another classes bonus feats eg Monk's Stunning Fist?

edit: oh wait, the duelist only has a situational combat reflexes anyway, not the actual feat. never mind that

Still, this could be handy to know in other circumstances, and my second question hopes for an answer too :P

[Psyren]

Well, aside from the built-in retraining the Fighter gets for its bonus feats, there is also the universal retraining system (http://www.d20pfsrd.com/basics-ability-scores/more-character-options/retraining) that will let you reconfigure your entire build from the ground up. So the point may be moot.