Hi Mostel,
I'm not at all the target audience for this question as I really don't find either watch appealing, but if forced to choose, I'd go with the Centigraphe.
I find the Duometre to be a huge amount of complication without much real innovation and little (if any) performance gain for all the trouble. It's like adding an extra engine to your car so that you have more power for passing on the freeway. The game is not worth the candle as my friend Jack likes to say.
The Centigraphe on the other hand is a more whimsical piece that, on some level, knows it cannot do at all what it's name implies, but still attempts to do so with great style. It's beautiful and self-serious in its presentation and, to my eye, much more graceful than the Duometre.
Let us not be confused: I'd take a Speedy or any of several handfuls of other "regular" chronographs over either one, but if I'm choosing at gun-point... 
_john