Routing Help

Why do they need to be routed identically? is it some sort of crazy asynchronous design?

Basically what you want to do isnt possible - the synthesisor will do all sorts of optimisations before it even reaches the fitter, and then the fitter will put it all in to make it fit and meet the timing requirements. you may be able to set timing requirements to make them very similar, or if you get really extream you could RLOC the lot.

But it would be a lot of hard work (and you would be doing the fitter's very very complicated job).