I was talking about the reaction of airplanes with counter rotating propellers with a critical engine failure
No you weren't. You made no mention whatsoever of this question. You asked whether anyone had any comment about the Duchess's suitability for multi-engine training. You got (from me at least) an answer appropriate to the vagueness of your question. Had you asked the question you meant to ask, you might have got an answer of some use to you.
Don't assume that others have a crystal ball to help them divine your meaning. Make your questions clear and unambiguous. Luckily for you, Rob's Dad has more patience than I do - but then he doesn't have to read stuff like this over and over again!
Scroggs